Module incorporating a capacitor, method for manufacturing the same, and capacitor used therefor

ABSTRACT

A module incorporating a capacitor, the module including a circuit board and a layer incorporating a capacitor, wherein the circuit board includes a wiring layer and a via contact for providing electrical conductivity to a cathode and an anode of the capacitor. The layer incorporating the capacitor includes a ferromagnetic layer integrated with at least a portion of a surface of the capacitor, and in the circuit board or the layer incorporating the capacitor a coil is wound around the capacitor, or an inductor component is disposed in parallel with the capacitor. Accordingly, a module incorporating a capacitor in which miniaturization, a higher density and a reduced thickness have been achieved, as well as a method for producing the module and a capacitor used for the module, are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Division of application Ser. No. 10/944,311, filedSep. 17, 2004, which application is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to modules incorporating a capacitor,methods for manufacturing the same, and capacitors used therefor.

2. Description of the Related Art

In recent years, with the progress in the miniaturization of variousdevices and the increase in density of capacitors constituting thedevices, there is an increasing demand for the miniaturization of thecapacitor itself. Moreover, with the development of higher speeddevices, high-speed response and low-loss properties are demanded forcapacitors equipped with a capacitor unit. In order to meet thesedemands, three-dimensional modules incorporating a capacitor in which acapacitor or a semiconductor component (active component) provided witha capacitor is incorporated in a substrate have been developedvigorously (see e.g., JP H11-220262A).

At this time, in order to attain both a higher density and a reducedthickness for capacitors constituting a module incorporating acapacitor, it is necessary to use a high-performance capacitor whosesize and thickness are small. However, as the size and the thickness ofthe capacitors become increasingly small, the handling and the mountingof the capacitors have become particularly difficult.

When the capacitor unit is a capacitor, a film-type solid electrolyticcapacitor is suitable as a capacitor to be incorporated in a substratefor producing a small or thin module incorporating a capacitor. However,the film-type solid electrolytic capacitor is particularly difficult tohandle as a single component, since it is extremely thin although havinga large capacitance.

Here, a conventional film-type solid electrolytic capacitor is describedwith reference to FIG. 12. FIG. 12 is a cross-sectional view showing theconfiguration of a typical conventional film-type solid electrolyticcapacitor. The conventional film-type solid electrolytic capacitor shownin FIG. 12 is provided with: an anode valve metal 121, such as aluminum;a dielectric as a solid electrolyte, and is formed on a portion of thesurface of the dielectric oxide film 122; and a cathode currentcollector layer 124, such as a carbon layer or an Ag (silver) pastelayer, formed on the surface of the solid electrolyte layer 123; and aninsulating resin portion 125 formed on a portion of the surface of thedielectric oxide film 122 (see e.g., pars. [0003] and [0004] and FIG. 11of JP2002-198264A). It should be noted that in the conventionalfilm-type solid electrolytic capacitor shown in FIG. 12, the insulationbetween the anode valve metal 121 and the cathode current collector 124is ensured by providing the insulating resin portion 125.

Since such a film-type solid electrolytic capacitor generally has athickness of 0.2 mm or less, it tends to be deformed by an externalforce and physically damaged. Therefore, instead of handling thefilm-type solid electrolytic capacitor as a single component, aplurality of the film-type capacitors are enclosed in a package to forma chip, thus preventing deformation or damage, while allowing them to behandled readily by suction utilizing an air pressure difference (seee.g., FIGS. 1 and 3 of JP H6-168855A).

Usually, when a capacitor is mounted using a mounting device such as achip mounter, the capacitor is first held (by vacuum suction) by atransport member with an air pressure difference, then moved to adesired position on a substrate, with the capacitor held by thetransport member, followed by separating the capacitor from thetransport member by suspending the vacuum suction. Therefore, it hasbeen difficult to mount on a substrate a single conventional capacitorunit, which is small and has weak mechanical strength, as a singlecomponent.

In the case of the film-type solid electrolytic capacitor, it has beenparticularly difficult to handle the capacitor as a single component,since it is small and very thin, with its thickness being 0.2 mm orless. Furthermore, when such a film-type solid electrolytic capacitor ismounted onto a substrate as a single component, the functions of thecapacitor may be damaged fatally by, for example, peeling of the surfacelayer. Moreover, the surface layer is not flat, so that a sufficientsuction force may not be obtained by vacuum suction and a suctionfailure or falling thus may occur during transporting the capacitor.Therefore, it has been extremely difficult to perform a conventionalautomatic mounting.

On the other hand, a conventional capacitor formed as a chip byenclosing a plurality of capacitors in a package can be handled moreeasily, than a capacitor as a single component. However, in this case,the capacitor becomes large physically, and a plurality of capacitorunits are concentrated on the same portion on the substrate, hinderingthe flexibility of the circuit design. This results in the necessity toprovide a more complex or longer wiring. Furthermore, when theconventional capacitor formed as a chip is embedded in a multi-layeredcircuit board, it is necessary to provide an insulating layer of athickness corresponding to the height of the capacitor. Therefore, inthe case of using the conventional capacitor formed as a chip, it hasbeen difficult to realize a further reduction in the size and thethickness of a module incorporating a capacitor.

SUMMARY OF THE INVENTION

Therefore, in order to solve the above-described conventional problems,the present invention provides a module incorporating a capacitorcapable of realizing miniaturization, a higher density and a reducedthickness and a method for producing the same, as well as a capacitorused for such a module.

A module incorporating a capacitor according to the present invention isa module incorporating a capacitor, the module including a circuit boardand a layer incorporating a capacitor, wherein the circuit boardincludes a wiring layer and a via contact for providing electricalconductivity to a cathode and an anode of the capacitor, wherein thelayer incorporating the capacitor includes a ferromagnetic layerintegrated with at least a portion of a surface of the capacitor. In thecircuit board or the layer incorporating the capacitor, a coil is woundaround the capacitor, or an inductor component is disposed in parallelwith the capacitor.

A method for producing a module incorporating a capacitor according tothe present invention is a method for producing a module incorporating acapacitor, the module including a circuit board, a layer incorporating acapacitor integrated with the circuit board and a ferromagnetic layerintegrated with at least a portion of a surface of the capacitor, themethod comprising: transporting the capacitor to a circuit boardincluding a first wiring layer on a surface thereof by a magneticaction, followed by mounting the capacitor onto the circuit board; andplacing an electrically insulating substrate and a second circuit boardincluding a second wiring layer in this order from the capacitor side ofthe circuit board, followed by embedding the capacitor in theelectrically insulating substrate by heating and pressing. In one of thesteps, a coil is wound around the capacitor, or an inductor component isdisposed in parallel with the capacitor in the circuit board or thelayer incorporating the capacitor.

A capacitor according to the present invention is a capacitor used for amodule incorporating a capacitor, the module including a circuit boardand a layer incorporating a capacitor, wherein a ferromagnetic layer isintegrated with at least a portion of a surface of the capacitor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic side view of a capacitor according to Embodiment1 of the present invention, and FIG. 1B is a plan view of the samecapacitor.

FIGS. 2A to C are plan views for illustrating the shape of aferromagnetic portion of the capacitor according to Embodiment 1 of thepresent invention.

FIG. 3A is a cross-sectional view of a capacitor according to Embodiment2 of the present invention, and FIG. 3B is a plan view of the samecapacitor.

FIG. 4 is a cross-sectional view of a capacitor according to Embodiment3 of the present invention.

FIG. 5A is a cross-sectional view of a module incorporating a capacitoraccording to Embodiment 4 of the present invention, and FIG. 5B is aperspective view, focusing on the coil of the same module.

FIGS. 6A to C are cross-sectional views showing a production process ofthe module incorporating a capacitor according to Embodiment 4 of thepresent invention.

FIG. 7 is a cross-sectional view showing a production process of themodule incorporating a capacitor according to Embodiment 4 of thepresent invention.

FIG. 8A is a cross-sectional view of a module incorporating a capacitoraccording to Embodiment 5 of the present invention, and FIG. 8B is aplan view, focusing on the coil of the same module.

FIG. 9 is a cross-sectional view of a module incorporating a capacitoraccording to Embodiment 6 of the present invention.

FIG. 10 is a cross-sectional view of a module incorporating a capacitoraccording to Embodiment 7 of the present invention.

FIGS. 11A to D are cross-sectional views showing a production process ofthe module incorporating a capacitor according to Embodiment 7 of thepresent invention.

FIG. 12 is a schematic cross-sectional view showing a conventional solidelectrolytic capacitor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the present invention, “ferromagnetic material” refers to a substancewhose constituent atoms each has a magnetic moment and are aligned inthe same direction and that is magnetized in that direction when amagnetic field is applied and exhibits residual magnetization even afterthe magnetic field is removed. Any ferromagnetic material changes into aparamagnetic material when its temperature is increased, and thetemperature at which this change takes place is called the Curie point.In the present invention, it is preferable to use a ferromagneticmaterial that exhibits ferromagnetism in the actual operatingtemperature range, including, for example, from room temperature (20°C.) to about 150° C. or lower. It is more preferred to use a softmagnetic material as a ferromagnetic material. It is preferable that theferromagnetic material used in the present invention ensures sufficientperformance of an inductor formed in the module, and has a saturationflux density per capacitor of at least 10 mT (milli Tesla), in view ofthe suction and the like performed during mounting of components.

A capacitor according to the present invention is provided with aferromagnetic portion. More specifically, a capacitor of the presentinvention may be a capacitor (hereinafter, also referred to as“capacitor A”) formed by integrating a ferromagnetic portion with acapacitor unit by, for example, bonding, or a capacitor (hereinafter,also referred to as “capacitor B”) formed by providing a ferromagneticportion at least on a portion of the components that are necessary toform a capacitor unit. Alternatively, a capacitor of the presentinvention may be a combination of these two configurations. It is to benoted that the “integration” as used herein means bonding aferromagnetic material to a portion of a capacitor or providing aferromagnetic portion at least on a portion of the components that arenecessary to form a capacitor unit.

With these configurations, the ferromagnetic portion serves as amagnetic core and also serves as a magnet in the presence of an externalmagnetic field, so that the capacitor can be transported by a magneticaction. More specifically, it is possible to reliably perform atransport operation including: causing the capacitor to be attracted byan electromagnet by a magnetic attraction; moving the capacitor to adesired position by moving the electromagnet; and separating thecapacitor from the electromagnet by eliminating an external magneticfield generated by the electromagnet.

With these configurations, even a capacitor including only a singlecapacitor unit, which is highly flexible as a single component and whosesurface is very rough or in an asymmetrical shape, can be transportedmore easily and reliably, than a conventional suction (vacuum suction)using an air pressure difference. Furthermore, the use of a mountercapable of mounting circuit components with a magnetic action makes itpossible to mount a capacitor including a single capacitor unit onto asubstrate, and to realize automatic mounting of the capacitor.

It is preferable that a capacitor according to the present invention isof the surface mount type, from the viewpoint of performing mountingwith a magnetic action, particularly automatic mounting. In addition, acapacitor of the present invention further may include, for example, aninsulating protective film for ensuring the electrical insulation fromthe outside and a protective film for reducing the damage caused by anexternal force.

For example, the capacitor A of the present invention may have aconfiguration in which the ferromagnetic portion is a ferromagnetic foilbonded onto a capacitor unit (hereinafter, also referred to as“foil-type ferromagnetic portion”), or a configuration in which theferromagnetic portion includes a resin composition formed on a capacitorunit and a plurality of ferromagnetic particles dispersed and fixed inthe resin composition (hereinafter, also referred to as“particle-dispersed ferromagnetic portion”).

Preferably, the ferromagnetic portion is disposed in the vicinity of thesurface of the capacitor and more preferably, it is exposed on thesurface of the capacitor. The reason is that the closer theferromagnetic portion is to the surface, the stronger its attractingforce to an external magnet. In the case of a capacitor whose mountingsurface, which is the surface placed on the substrate side, ispreviously determined, it is preferable that the ferromagnetic portionis disposed on a surface different from the mounting surface. Further,when the capacitor unit has a substantially rectangular solid shape, itis more preferable that the ferromagnetic portion is disposed on asurface opposite to the mounting surface.

Examples of the ferromagnetic material forming the ferromagnetic portioninclude: ferromagnetic metals such as Fe, Ni and Co; ferromagneticalloys including a plurality of different ferromagnetic metals; andferromagnetic compounds including a ferromagnetic metal. Examples of theferromagnetic alloys include an iron-nickel (Fe—Ni) alloy, and examplesof the ferromagnetic compounds include a ferrite.

When the ferromagnetic portion is the foil-type ferromagnetic portion,the capacitor A of the present invention may have a configuration inwhich the ferromagnetic foil is fixed onto the capacitor unit via anadhesive. Alternatively, it may have a configuration in which theferromagnetic foil is fixed directly onto the capacitor unit, withoutdisposing any other member between the ferromagnetic foil and thecapacitor unit. The capacitor A of the present invention also can beprovided by bonding the ferromagnetic foil to an existing capacitorunit. Examples of the ferromagnetic foil include a foil composed only ofa ferromagnetic material (e.g., an iron foil, a nickel foil, a cobaltfoil, an iron-nickel foil and a ferrite foil), and a foil containing aferromagnetic material as the main component (e.g., an iron-siliconfoil, an iron-aluminum-silicon foil, an iron-boron foil and acobalt-boron foil). Here, “main component” means a component thatconstitutes at least 50 mass % and less than 100 mass % of theferromagnetic foil. Preferably, the ferromagnetic foil has a thicknessin the range of 5 μm to 100 μm.

When the ferromagnetic portion is the particle-dispersed ferromagneticportion, the resin composition serves as an adhesive, so that theferromagnetic particles can be fixed onto the capacitor unit withoutusing an adhesive separately. In addition, the capacitor A of thepresent invention may have a configuration in which a sheet memberincluding a resin composition and ferromagnetic particles is used as theferromagnetic portion, and the sheet member is bonded to the capacitorunit. When the ferromagnetic portion is the particle-dispersedferromagnetic portion, the ferromagnetic portion can be shaped easily,so that a ferromagnetic portion with a desired shape can be formedeasily.

The particle-dispersed ferromagnetic portion may include only one kindof ferromagnetic particles, or may include a plurality of differentkinds of ferromagnetic particles. Examples of the ferromagneticparticles included in the particle-dispersed ferromagnetic portioninclude particles composed only of ferromagnetic materials (e.g., ironparticles, nickel particles, cobalt particles, iron-nickel alloyparticles and ferrite particles) and particles containing ferromagneticmaterials as the main component (e.g., iron-silicon particles,iron-aluminum particles, iron-boron particles and cobalt-boronparticles). Here, “main component” means a component that constitutes atleast 50 mass % and less than 100 mass % of the constituents of theparticles. The ferromagnetic particles preferably have an averageparticle size of at least 0.01 μm and at most 50 μm, and more preferablyat least 1 μm and at most 30 μm.

As the resin serving as a binder for the ferromagnetic particles, it ispreferable to use a thermosetting resin. In this case, the ferromagneticparticles are firmly fixed onto the capacitor unit by curing thethermosetting resin.

It is preferable that the above-described thermosetting resin is atleast one selected from the group consisting of an epoxy resin, apolyimide resin, a polyphenylene ether resin, a phenol resin, afluorocarbon resin and an isocyanate resin. Preferably, the mixing ratioof the ferromagnetic particles and the thermosetting resin is such thatthe mixing proportion of the ferromagnetic particles is in the range of85 mass % to 98 mass %, based upon the total mass taken as 100 mass %.Preferably, the mixture of the ferromagnetic particles and thethermosetting resin is in the form of a sheet. and the thickness of thesheet after curing is in the range of 5 μm to 100 μm.

The capacitor A has a structure in which the ferromagnetic portionprevents the occurrence of positional or rotational shift of thecapacitor when the capacitor is mounted onto an external substrate. Morespecifically, it is preferable that the surface of the ferromagneticportion that is located opposite to the capacitor unit has asubstantially concave polygonal outline. With this configuration, it ispossible to prevent the occurrence of positional or rotational shiftmore favorably than a configuration in which the surface has a circularor convex polygonal outline. Here, the substantially concave polygonalshape includes, for example, a concave polygon and a shape in which atleast a portion of the sides forming a concave polygon is replaced by acurved line. In addition, “convex polygon” means a polygon in which allinterior angles are less than 180°, and “concave polygon” means apolygon in which at least one interior angle is greater than 180°.“Rotational shift” means a shift resulting from the rotational movementof the capacitor, and “positional shift” means a shift resulting fromthe parallel movement of the capacitor. Examples of the concavepolygonal shape include a cross-shape, a T-shape and a U-shape. Itshould be noted that the surface outline of the ferromagnetic portion isnot limited to a substantially concave polygonal shape. In addition, itis preferable that the location of the ferromagnetic portion isdetermined taking into account the center of gravity of the capacitor.Preferably, the ferromagnetic portion is disposed such that the centerof gravity of the capacitor and that of the ferromagnetic are aligned ona vertical line.

With a structure in which the ferromagnetic portion prevents rotationalor positional shift, the rotational or positional shift of the capacitorduring attracting the capacitor to a transport member (electromagnet)can be corrected with a magnetic force, by shaping the surface of theattracting side of the transport member correspondingly to the shape ofthe surface outline of the ferromagnetic portion. As a result, thepositional accuracy during attracting is improved. Therefore, thepositional accuracy at the time of transporting the capacitor to adesired position generally depends solely on the positional accuracy ofmovement of the transport member (electromagnet), so that thetransporting can be performed with an extremely high accuracy. In thecase of mounting the capacitor with a high density, the positionalaccuracy in placing the capacitor is important. A capacitor having thisconfiguration can reduce margins because of its high positionalaccuracy. This facilitates an increase of the density of the capacitor.To improve the positional accuracy during attracting, it is preferable,for example, to arrange a low friction, non-magnetic material on thesurface of the transport member. The reason is that the positionalaccuracy easily can be corrected with a magnetic force. Examples of thelow friction, non-magnetic material include non-magnetic metals such ascopper, silver and gold, and resins such as polytetrafluoroethylene.Alternatively a low friction layer made of these low friction,non-magnetic materials may be formed on the ferromagnetic portion.

The capacitor A has a configuration in which the capacitor unit is anelectrolytic capacitor including: a valve metal including a capacitanceforming portion and an electrode lead portion; a dielectric oxide filmdisposed on the surface of the valve metal; a solid electrolyte disposedon the surface of the capacitance forming portion, with the dielectricoxide film interposed between the solid electrolyte and the capacitanceforming portion; and a current collector that is formed on the surfaceof the solid electrolyte and is electrically insulated from the valvemetal, and a ferromagnetic portion is disposed on the current collector.With this configuration, an electrolytic capacitor, which is mostdifficult to be transported as a single component among variouscapacitor units, can be handled easily as a single component.

In the following, a method for producing the capacitor is described.According to a first method for producing a capacitor as describedabove, it is possible to produce a capacitor A including a foil-typeferromagnetic portion bonded to a capacitor unit as a ferromagneticportion. In a step of working a ferromagnetic foil into a predeterminedshape, the ferromagnetic foil can be worked into a predetermined shapeby, for example, cutting or punching. In a step of bonding aferromagnetic portion, the ferromagnetic foil can be bonded to thecapacitor unit with a liquid or paste adhesive, or an adhesive sheet. Itis possible to employ either a method of bonding the ferromagnetic foilto the capacitor unit after depositing the adhesive or the adhesivesheet to the ferromagnetic foil, or a method of bonding theferromagnetic foil to the capacitor unit after depositing the adhesiveor the adhesive sheet to the capacitor unit.

Furthermore, according to a second method for producing a capacitor asdescribed above, it is possible to produce a capacitor A including aparticle-dispersed ferromagnetic portion as a ferromagnetic portion. Ina step of depositing a paste mixture, the paste mixture can be depositedby an application process, or a printing process such as screenprinting, for example. In a step of curing the paste mixture, the pastemixture can be cured by a heating process using a heat source, or by aheating process using light irradiation.

The first or second method for producing a capacitor A further includesa step of forming a capacitor unit, and the step of forming a capacitorunit includes a step of forming a dielectric oxide film on the surfaceof a valve metal, a step of forming a solid electrolyte on a portion ofthe surface of the dielectric oxide film and a step of forming a currentcollector on the surface of the solid electrolyte. With thisconfiguration, it is possible to produce a capacitor A including anelectrolytic capacitor as a capacitor unit.

According to a third method for producing a capacitor as describedabove, it is possible to produce a capacitor A including an electrolyticcapacitor as a capacitor unit and a foil-type ferromagnetic portionfixed directly to the capacitor unit. This production method eliminatesthe need to deposit the adhesive or the adhesive sheet on the foil-typeferromagnetic portion, thus simplifying the production process.

The capacitor B has, for example, a configuration in which a capacitorunit includes a resin composition, and the ferromagnetic portion isformed by a plurality of particles dispersed and fixed in the resincomposition. With this configuration, the ferromagnetic portionpossesses ferromagnetism without fail, so that it is possible toreliably perform a transport operation including: causing the capacitorto be attracted by an electromagnet with a magnetic attraction, movingthe capacitor to a desired position by moving the electromagnet; andseparating the capacitor from the electromagnet by eliminating anexternal magnetic field generated by the electromagnet, as in the caseof the above-described capacitor A. Furthermore, it is possible to formthe resin composition, as well as to fix the ferromagnetic portion.

As the ferromagnetic particles forming the ferromagnetic portion of thecapacitor B, it is possible to use the same ferromagnetic particles asthose of the above described capacitor A.

The capacitor B has a configuration in which the capacitor unit is anelectrolytic capacitor including: a valve metal including a capacitanceforming portion and an electrode lead portion; a dielectric oxide filmdisposed on the surface of the valve metal; a solid electrolyte disposedon the surface of the capacitance forming portion, with the dielectricoxide film interposed between the solid electrolyte and the capacitanceforming portion; and a current collector that is disposed on the surfaceof the solid electrolyte and is electrically insulated from the valvemetal, wherein the current collector of the electrolytic capacitor is aresin component. With this configuration, even in the case of anelectrolytic capacitor component, which is most difficult to betransported as a single component among various capacitor units, thecapacitor unit can be handled easily as a single component.

Next, according to a fourth method for producing a capacitor asdescribed above, it is possible to produce a capacitor B including anelectrolytic capacitor as a capacitor unit, wherein a ferromagneticportion is formed on the current collector of the electrolyticcapacitor. With this configuration, the ferromagnetic portion is notdisposed on the capacitor unit, unlike the capacitor A, and it ispossible to produce a capacitor with an even smaller thickness.Furthermore, since it is not necessary to dispose the ferromagneticportion on the capacitor unit, the production process can be simplified,as compared with the capacitor A.

In the following, a module incorporating a capacitor according to thepresent invention is described. The module incorporating a capacitorincludes a ferromagnetic layer integrated with at least a portion of oneof the surfaces of the capacitor. In the circuit board or thecapacitor-incorporating layer of the module, a coil surrounding thecapacitor is disposed, or an inductor component is disposed in parallelwith the capacitor, so that the module incorporating a capacitor hasachieved miniaturization, a higher density and a reduced thickness. Thatis, each single capacitor unit can be embedded in an insulating layer ina multi-layered circuit board, making it possible to reduce thethickness of the module incorporating a capacitor, and to increase thedensity of the capacitor incorporated in the module incorporating acapacitor.

Together with a capacitor, the module incorporating a capacitor of thepresent invention may incorporate a passive device such as a resistor ora coil, or may incorporate an active device (e.g., a semiconductordevice, a semiconductor package, a crystal oscillator and a surfaceacoustic wave (SAW) filter). In this specification, “interlayer contact”includes, for example, a via contact that electrically connects twoadjacent wiring layers, a contact that penetrates a plurality ofelectrically insulating layers and connects wiring layers that areseparated from each other by at least one layer and a through holecontact formed on the side wall of a through hole penetrating thecapacitor-incorporating layer.

The module incorporating a capacitor of the present invention includes acapacitor unit and a ferromagnetic portion disposed on the capacitorunit, and the ferromagnetic portion is disposed on a surface of thecapacitor unit that is different from the surface facing theabove-described first wiring layer. With this configuration, thecapacitor can be mounted with high positional accuracy with a magneticaction, thus providing a high-performance substrate incorporating acapacitor unit that does not cause disconnection of wiring. Preferably,the ferromagnetic portion is formed on a surface of the capacitor thatis opposite to the mounting surface. In this case, the capacitor can betransported with a smaller magnetic force than the case where theferromagnetic portion is formed on the surface (mounting surface) facingthe first wiring layer at the time of mounting of the capacitor, so thatit is also possible to reduce the harmful effect of the magnetic forceapplied to other capacitors.

The module incorporating a capacitor of the present invention includes acapacitor unit and a ferromagnetic portion fixed in a resin composition,and the resin composition in which the ferromagnetic portion is formedconstitutes a portion of a surface of the capacitor that is differentfrom the surface facing the first wiring layer. With this configuration,the capacitor can be mounted with high positional accuracy with amagnetic action, thus providing a high-performance board incorporating acapacitor unit that does not cause the disconnection of wirings.

In the module incorporating a capacitor of the present invention, it ispreferable that the first wiring layer and the capacitor described aboveare connected via a conductive adhesive containing a conductive powderand a thermosetting resin. With this configuration, the capacitor can bemounted at a relatively low temperature, so that it is possible to mounta capacitor having low heat resistance. Furthermore, when the currentcollector is a conductive resin composition as in a solid electrolyticcapacitor, it is possible to realize stable connection and lowresistance. There is no particular limitation with respect to theconductive powder, and it is possible to use silver, gold, copper andnickel, or alloys of these metals, for example. As the thermosettingresin, it is possible to use an epoxy resin, for example.

Preferably, the capacitor-incorporating layer is formed of a mixturecontaining an inorganic filler and a thermosetting resin. It is possibleto embed the capacitor in a state in which the thermosetting resin isuncured, followed by curing the thermosetting resin. The above-describedmixture may be used in the form of a sheet, or may be provided with acavity where the capacitor is embedded. Embedding the capacitor into theabove-described mixture in the form of a sheet is like pushing thecapacitor into a soft, clay-like material. The thermosetting resin isexcellent in heat resistance and insulation, and allows the capacitor tobe incorporated into a substrate at a relatively low temperature.Furthermore, the coefficient of linear expansion, the glass transitionpoint and the modulus of elasticity of the electrically insulating layercan be controlled by appropriately selecting the type of thethermosetting resin that constitutes the electrically insulating layer.Moreover, the coefficient of linear expansion, the thermal conductivityand the dielectric constant of the electrically insulating layer can becontrolled by appropriately selecting the type and amount of theinorganic filler that constitutes the electrically insulating layer.Accordingly, the capacitor-incorporating layer becomes an electricallyinsulating layer that has excellent surface flatness and high thermalconductivity and covers the capacitor reliably, without causing anydamage to the capacitor.

Preferably, the inorganic filler is at least one selected from the groupconsisting of SiO₂, Al₂O₃, MgO, TiO₂, BN, AlN and SiN₄. These canprovide a suitable thermal expansion coefficient and thermalconductivity.

Furthermore, the use of Al₂O₃, BN or AlN provides a module with highthermal conductivity. The use of MgO yields a favorable thermalconductivity and a large thermal expansion coefficient. The use of SiO₂(amorphous SiO₂ in particular) provides a light-weight module with asmall thermal expansion coefficient and a low dielectric constant.

Preferably, the thermosetting resin is at least one selected from thegroup consisting of an epoxy resins a polyimide resin, a polyphenyleneether resin, a phenol resin, a fluorocarbon resin and an isocyanateresin.

A preferable mixing ratio of the inorganic filler and the thermosettingresin is such that the mixing proportion of the inorganic filler is inthe range of 70 mass % to 95 mass % and the mixing proportion of thethermosetting resin is in the range of 5 mass % to 30 mass %.

Directly above the capacitor-incorporating layer, an inductor componentelectrically connected to a multi-layered wiring group is disposed. Withthis configuration, it is possible to focus leakage magnetic fieldsgenerated at the time of operating the inductor component. Furthermore,the module incorporating a capacitor of the present invention includes acoil that is formed by a portion of the multi-layered wiring group and aportion of a plurality of interlayer contacts and is formed directlyabove the capacitor. With this configuration, it is also possible tofocus leakage magnetic fields generated at the time of operating thecoil.

Alternatively, the module incorporating a capacitor of the presentinvention includes a coil that is formed by a portion of themulti-layered wiring group and a portion of a plurality of interlayercontacts, and the capacitor serves as the magnetic core of the coil.With this configuration, the ferromagnetic portion of the capacitor hasferromagnetism, so that it is possible to increase the inductance of thecoil.

It is preferable that the method for producing a module incorporating acapacitor includes the step of mounting a capacitor including:depositing a conductive adhesive on a predetermined area on the firstwiring layer; causing the capacitor to be attracted by an electromagnetwith the action of a magnetic field by passing an electric currentthrough a coil of the electromagnet; moving the capacitor attracted tothe electromagnet onto the circuit board such that the capacitor is incontact with the first wiring layer via the conductive adhesive; andseparating the capacitor from the electromagnet by turning off theelectric current passing through the electromagnet. With thisconfiguration, it is possible to attract and separate the capacitoreasily using the electromagnet, as well as to mount the capacitorreliably with high positional accuracy.

It is also preferable that the method for producing a moduleincorporating a capacitor according to the present invention includes astep of mounting a capacitor including: depositing a conductive adhesiveon a predetermined area on the first wiring layer; causing the capacitorto be attracted by an electromagnet with the action of a magnetic fieldby passing an electric current through a coil of the electromagnet;moving the capacitor attracted by the electromagnet onto the circuitboard such that the capacitor is in contact with the first wiring layervia the conductive adhesive; thereafter causing the ferromagnetic layerof the capacitor to generate heat by induction heating by applying analternating current to the coil of the electromagnet, thereby curing theconductive adhesive; and separating the capacitor from the electromagnetby turning off the electric current passing through the coil of theelectromagnet. With this configuration, it is possible to cure theconductive adhesive by electromagnetic induction heating at the sametime of performing the steps of attracting and separating the capacitorwith the electromagnet, thus simplifying the mounting process. Moreover,since the conductive adhesive can be cured while the capacitor is holdon the circuit board by the electromagnet, it is possible to achievehigh positional accuracy and stable connection resistance.

Further, it is also preferable that the method for producing a moduleincorporating a capacitor according to the present invention includes astep of mounting a capacitor including: moving the capacitor onto thecircuit board such that the capacitor is in contact with the firstwiring layer via the conductive adhesive; placing the circuit board ontoan magnet plate having a magnetic action such that the surface of thecircuit board on which the capacitor is not placed is in contact withthe magnet plate; and curing the conductive adhesive by heating, whilegenerating an attractive force between the capacitor and the firstwiring layer of the circuit board, thereby electrically connecting thecapacitor to the first wiring layer of the circuit board. With thisconfiguration, it is possible to achieve high positional accuracy andstable connection distance at the time of curing the conductiveadhesive, by using the attractive force between the magnet plate and thecapacitor. Furthermore, simultaneous mounting of a plurality ofcapacitors can be performed stably.

In the above-described module incorporating a capacitor of the presentinvention, each single capacitor unit can be embedded in an electricallyinsulating layer. Accordingly, it is possible to reduce the thickness ofthe module incorporating a capacitor, and to increase the density of acapacitor incorporated in the module.

Furthermore, it is preferable that the method for producing a moduleincorporating a capacitor according to the present invention includesthe step of forming a substrate that includes: forming an electricallyinsulating substrate from a mixture of an inorganic filler and athermosetting resin, followed by forming a through hole in theelectrically insulation substrate. This is because the thermosettingresin is excellent in heat resistance and electrical insulation, andallows the capacitor to be incorporated into a substrate at a relativelylow temperature. Furthermore, the coefficient of linear expansion, theglass transition point and the modulus of elasticity of the electricallyinsulating layer can be controlled by appropriately selecting the typeof the thermosetting resin forming the electrically insulating layer.Moreover, the coefficient of linear expansion, the thermal conductivityand the dielectric constant of the electrically insulating layer can becontrolled by appropriately selecting the type and the amount of theinorganic filler forming the electrically insulating layer. Thisprevents, for example, the disconnection of the wiring resulting fromthe deformation of the electrically insulating layer, so that ispossible to obtain a highly reliable module incorporating a capacitorwith excellent heat resistance and high speed response.

In a DC-DC converter, which is one of the applications of a capacitor,it is preferable that the electrolytic capacitor component of thepresent invention is embedded at least in an electrically insulatinglayer, and an inductor and a semiconductor capacitor are electricallyconnected and integrated into one piece. With this configuration, it isalso possible to embed each single capacitor unit in the electricallyinsulating layer. Accordingly, it is possible to obtain a high-densityDC-DC converter that has desired high capacitance and low ESR(equivalent series resistance, which represents the resistance componentof a capacitor) and in which a capacitor with a reduced thickness ismounted and integrated.

It is preferable that the inductor of the DC-DC converter is connectedelectrically to one of wiring layers forming a multi-layered wiringgroup and is disposed directly above the capacitor. The reason is thatthis makes it possible to focus leakage magnetic fields generated at thetime of operating the inductor. Further, it is preferable that theinductor of the DC-DC converter is a coil formed by a portion of themulti-layered wiring group and a portion of a plurality of interlayercontacts, and the capacitor serves as the magnetic core of the coil.With this configuration, it is possible to increase the inductance ofthe coil.

According to the present invention, ferromagnetic means are disposed onor within a capacitor unit included the capacitor, so that the capacitorunit easily can be handled as a single component. In particular, thecapacitor unit can be mounted easily onto a board as a single component.Furthermore, the capacitor can be transported with a magnetic action,realizing automatic mounting. With the use of the capacitor of thepresent invention, it is possible to achieve stronger adhesion betweenthe capacitor and a substrate, thereby improving the mountability of thecapacitor. With the use of the capacitor of the present invention, it isalso possible to achieve miniaturization and higher density for variousmodules incorporating a capacitor.

Hereinafter, preferred embodiments of the present invention aredescribed with reference to the accompanying drawings as necessary. Inthe drawings, the same reference numerals are given to components thatare substantially the same.

Embodiment 1

A capacitor according to the present invention is described withreference to FIG. 1. FIG. 1A is a schematic side view of the capacitor,and FIG. 1B is a schematic plan view of the capacitor. The capacitor isa surface mount type capacitor whose overall shape is substantially thatof rectangular solid.

The capacitor includes a capacitor unit 10, connection terminals 13 aand 13 b disposed at both ends of the capacitor unit 10 and aferromagnetic foil 12 bonded onto the capacitor unit 10. In thiscapacitor, the reverse side relative to the principal surface 11, onwhich the ferromagnetic foil 12 is formed, serves as a mounting surface14.

The above-described capacitor is produced as follows. First, aferromagnetic foil 12 is formed in a predetermined shape by cutting orpunching. A liquid or paste adhesive is applied onto a previouslyproduced capacitor unit 10 provided with connection terminals 13 a and13 b. Subsequently, the ferromagnetic foil 12 formed in a predeterminedshape is placed on the capacitor unit 10. The ferromagnetic foil 12 isfixed onto the capacitor unit 10 by drying or curing the adhesive,forming a foil-type ferromagnetic portion (ferromagnetic portion).

Preferably, the surface mount type capacitor is worked into a generallyrectangular shape, regardless of the type (e.g., an electrolyticcapacitor, a thin film capacitor, a film-wound capacitor or a laminatedceramic capacitor) of the capacitor unit 10.

This capacitor is configured such that the center of gravity of thecapacitor unit 10 and that of the ferromagnetic foil 12 are aligned in aperpendicular direction. Compared with a configuration in which theferromagnetic foil 12 is disposed at a different location, thisconfiguration permits more stable attraction when the capacitor isattracted and raised by an electromagnet (transport member), therebypreventing the capacitor from falling during a transport operation.

While the surface of the attracted side of the ferromagnetic foil 12shown in FIG. 1B has a rectangular (convex polygonal) outline, otherconfigurations for preventing positional or rotational shift moreeffectively during transporting the capacitor and during attracting ofthe capacitor by the electromagnet are described with reference to FIGS.2A to C. FIGS. 2A to C are plan views showing the surface of theattracted side of the ferromagnetic portions with a configurationcapable of preventing rotational or positional shift during mounting thecapacitor to a substrate. FIG. 2A shows a ferromagnetic portion having across-shaped outline, FIG. 2B shows a ferromagnetic portion having aT-shaped outline and FIG. 2C shows a ferromagnetic portion having aU-shaped outline.

When the capacitor includes the ferromagnetic foils 12 with any of theoutlines shown in having the outlines shown in FIGS. 2A to C, thedifference between the attracting force when the attracting step isperformed accurately and the attracting force when a minute rotationalor positional shift occurs is greater than in the case of a capacitorincluding the ferromagnetic foil 12 having a rectangular (convexpolygonal) outline shown in FIG. 1B. This results in a strongerattracting force that allows the capacitor to be attracted to anaccurate position, thereby preventing rotational or positional shift.

In the case of the capacitor shown in FIGS. 1A and B, the ferromagneticfoil 12 is disposed only on the principal surface 11, which is thesurface opposite to the mounting surface 14. However, it is sufficientthat the ferromagnetic foil is disposed at least at a portion of theprincipal surface 11. The ferromagnetic foil further may be applied tothe side surface of the capacitor unit 10, or to the mounting surface14. When the ferromagnetic foil is electrically conductive, however, theferromagnetic foil is disposed so as not to be in contact with either ofthe mutually separated connection terminals 13 a and 13 b.

Although the previously produced capacitor unit 10 equipped with theconnection terminals 13 a and 13 b is used in the above-describedproduction method, it is possible to produce a capacitor byconsecutively forming the capacitor unit 10, the connection terminals 13a and 13 b and the ferromagnetic foil 12. In this case, it does notmatter which of the connection terminals 13 a and 13 b and theferromagnetic foil 12 is formed first.

Although the adhesive is applied to the capacitor unit 10 in theproduction method of the present embodiment, it is possible to produce acapacitor with a similar configuration by applying the adhesive to theferromagnetic foil worked into a predetermined shape and placing theferromagnetic foil with the adhesive onto the capacitor unit 10.Furthermore, although a liquid or paste adhesive is used in theproduction method of this embodiment, it is possible to use a capacitorwith a similar configuration by using an adhesive sheet in place of theadhesive. In the case of using an adhesive sheet, it is also possible toproduce a capacitor by placing the adhesive sheet on the capacitor unit,followed by placing the ferromagnetic foil 12 on the capacitor unit withthe adhesive sheet interposed between the capacitor unit and theferromagnetic foil 12, or by placing the adhesive sheet on theferromagnetic foil 12, followed by placing the ferromagnetic foil 12 onthe capacitor unit with the adhesive sheet interposed between thecapacitor unit and the ferromagnetic foil 12.

Although a configuration in which the ferromagnetic foil 12 is bonded tothe capacitor unit 10 is described above, it is possible to employ aconfiguration including, in place of the ferromagnetic foil 12, aparticle-dispersed ferromagnetic portion (ferromagnetic portion)containing a resin composition and ferromagnetic particles dispersed andfixed in the resin composition. In the case of this configuration, acapacitor can be produced as follows.

First, a paste mixture is prepared by mixing a resin, which will laterform a resin composition, with a powder of ferromagnetic particles.Next, the paste mixture is deposited onto a previously producedcapacitor unit 10 equipped with connection terminals 13 a and 13 b. Bydrying or curing the paste mixture, the paste mixture is fixed onto thecapacitor unit 10, forming a ferromagnetic portion. Examples of themethod for depositing the paste mixture on the capacitor unit 1 includean application process and a printing process such as screen printing.In the case of depositing the paste mixture using a printing processsuch as screen printing, the ferromagnetic portion easily can be formedin a desired shape by varying the shape of the printing plate. Here, itis preferable that a thermosetting resin is used as the resin. Thereason is that in the case of using a thermosetting resin, theparticle-dispersed ferromagnetic portion and the capacitor unit can befixed to each other firmly by curing the thermosetting resin by heating.

Embodiment 2

In Embodiment 2 of the present invention, a capacitor A (hereinafter,referred to as “electrolytic capacitor component A”) including anelectrolytic capacitor as a capacitor unit and a ferromagnetic portionformed on the electrolytic capacitor is described with reference toFIGS. 3A and B. FIG. 3A shows a cross-sectional view, and FIG. 3B showsa plan view. FIG. 3A is a cross-sectional view taken on the line I-I inFIG. 5B.

The electrolytic capacitor component A includes: an anode valve metal21; a dielectric oxide film 22; a solid electrolyte 23; a cathodecurrent collector 24; an insulator 25 for ensuring the electricalinsulation between the anode valve metal 21 and the cathode currentcollector 24; and a ferromagnetic portion 12. It should be noted thatthe insulator 25 is not an essential component of the present invention,but preferably is provided for electrically insulating the anode valvemetal 21 and the cathode current collector 24 reliably.

The ferromagnetic portion 12 may be a foil-type ferromagnetic portionbonded onto the electrolytic capacitor, or a particle-dispersedferromagnetic portion fixed onto the electrolytic capacitor.Furthermore, the ferromagnetic portion 12 may be a foil-typeferromagnetic portion fixed directly onto the electrolytic capacitorwithout using an adhesive.

As shown in FIG. 3A, it is preferable that the surface of the anodevalve metal 21 is roughened. The reason is that this configurationincreases the surface area and thus increases the capacitance of theelectrolytic capacitor. Examples of the anode valve metal 21 include afoil made of at least one valve metal material selected from the groupconsisting of Al, Ta and Nb, and a sintered material made of at leastone valve metal material selected from the above-described group. Interms of cost and productivity such as workability, it is preferable touse an Al foil as the material of the anode valve metal 21, since an Alfoil is available at low cost and its surface can be roughened easily.

Examples of the solid electrolyte 23 include a conductive polymercomposition composed only of a conductive polymer, and a conductivepolymer composition containing a conductive polymer and a dopant. Interms of conductivity, it is preferable that a dopant is included in thesolid electrolyte 23, since it increases the conductivity of anddecreases the resistance of the solid electrolyte 23. Examples of theconductive polymer include polypyrrole, polythiophene and polyaniline.Examples of the dopant include ionized arylsulfonic acid such as analkylnaphthalene sulfonic acid and para-toluenesulfonic acid, andionized aryl phosphoric acid.

Examples of the cathode current collector 24 include a laminate formedby a carbon layer and one or a plurality of metal layers selected fromthe group consisting of a silver layer, a copper layer a nickel layerand an aluminum layer that is formed on the carbon layer, and a laminateformed by a carbon layer and an alloy layer including a plurality ofmetal materials selected from the group consisting of silver, copper,nickel and aluminum that is formed on the carbon layer.

Examples of the insulator 25 include an insulating polymer compositionincluding an insulating polymer. Examples of the insulating polymerinclude polyimide, polyamide, polyphenylene ether (PPE), polyphenylenesulfide (PPS) or polyphenylene oxide (PPO).

Next, a method for producing an electrolytic capacitor component A ofthe present embodiment is described.

First, a case is described where the ferromagnetic portion 12 is afoil-type ferromagnetic portion bonded to the electrolytic capacitor, ora particle-dispersed ferromagnetic portion fixed to the electrolyticcapacitor is described.

First, the surface of a metal foil, which will later form an anode valvemetal 21, is roughened. For example, the surface of the metal foil,which will later form an anode valve metal 21, is electrolyticallyetched in an electrolyte containing hydrochloric acid as the maincomponent, by applying an alternating current to the metal foil.Consequently, the surface of the valve metal foil is roughened,obtaining an anode valve metal 21 with fine depressions and protrusionson its surface, as shown in FIG. 5A. In the case of using a metal foilas the anode valve metal 21, it is preferable to perform this step inorder to increase the surface area and thus to increase the capacitanceof the electrolytic capacitor. In the case of using a sintered materialas the anode valve metal 21, on the other hand, it is not necessary toperform this step, since a sintered material generally inherently hasfine concavities and convexities on its surface.

Next, a dielectric oxide film 22 is formed on the surface of the anodevalve metal 21. For example, the anode valve metal 21 is subjected toanodic oxidation in a neutral electrolyte, forming a dielectric oxidefilm 22 with a desired withstand voltage on the surface of the anodevalve metal. Generally, the dielectric oxide film 22 is formed into athickness in the range of at least 1 nm to at most 20 nm. It should benoted that the thickness of the dielectric oxide film 22 is not limitedto this range, and may be selected appropriately depending on thedesired properties of the electrolytic capacitor component.

Next, a solid electrolyte 23 is formed on a portion of the surface ofthe anode valve metal 21. For example, after masking a portion of theanode valve metal 21, a monomer of a conductive polymer is polymerizedby chemical polymerization or the combination of chemical polymerizationand electrolytic polymerization, using a solution containing a dopantand the monomer. The thus produced conductive polymer composition servesas a solid electrolyte 23. Furthermore, in the anode valve metal 21, aportion on which the solid electrolyte 23 is formed serves as acapacitance forming portion, and a portion on which the solidelectrolyte 23 is not formed serves as an electrode lead portion.Examples of the conductive polymer include polypyrrole, polythiopheneand polyaniline.

Next, an insulator 25 is formed on the anode valve metal 21 at aboundary between the capacitance forming portion and the electrode leadportion, with the dielectric oxide film 22 interposed between theinsulator 25 and the anode valve metal 21. The insulator 25 is formedby, for example, bonding an insulating tape to a predetermined position.To reliably ensure reliable insulation between the anode valve metal 21and a cathode current collector 24, which will be produced later, it ispreferable to provide sealing with the insulating tape.

Next, a cathode current collector 24 is formed on the surface of thesolid electrolyte 23. In the formation of a cathode current collector24, for example, a carbon layer is formed by applying a carbon pasteonto the surface of the solid electrolyte 23, followed by drying thecarbon paste, and a silver layer is formed by applying a silver pasteonto the carbon layer, followed by drying the silver paste by curing. Bythese steps, it is possible to form a cathode current collector 24 inwhich the carbon layer and the silver layer are laminated. Theapplication of the carbon paste and the silver paste can be performedusing dipping, for example. In this step, a metal foil such as Cu and Alcan be used, in place of the silver paste. In this case, after applyingthe carbon paste, the metal foil is placed on the carbon paste withoutcuring the carbon paste, followed by curing the carbon paste.Consequently, the metal foil is bonded to the solid electrolyte 23.

Next, treatments to repair defects in the dielectric oxide film 22 andto insulate the solid electrolyte 23 are conducted. The treatments areperformed by, for example, holding the resulting structure in ahigh-temperature and high-humidity atmosphere (e.g., temperature: 85° C.and relative humidity: 80% RH) at a predetermined voltage, followed bydrying. Upon completion of the treatments, an electrolytic capacitor canbe obtained.

Finally, a foil-type ferromagnetic portion or a particle-dispersedferromagnetic portion is formed on the electrolytic capacitor as theferromagnetic portion 12 in the same manner as in Embodiment 1 describedabove. By performing the above-described steps, it is possible toproduce an electrolytic capacitor component A with the configurationshown in FIGS. 3A and B.

Next, a second case is described in which the ferromagnetic portion 12is a foil-type ferromagnetic portion fixed directly to an electrolyticcapacitor. Until after the step in which the formation of the insulator25 is completed, the same steps are performed as in the case where theferromagnetic portion 12 is the above-described foil-type ferromagneticportion or the above-described particle-dispersed ferromagnetic portion.

In the formation of the cathode current collector 24 that is performedafter forming the insulator 25, a carbon layer is formed by applying acarbon paste onto the surface of the solid electrolyte 23 and curing thecarbon paste. Then, after applying a silver paste onto the carbon layer,a ferromagnetic foil worked into a predetermined shape is deposited onthe silver paste, without curing the silver paste. Next, a silver layeris formed by curing the silver paste by heating, while bonding theferromagnetic foil to the silver layer. By these steps, it is possibleto form a cathode current collector 24 in which the carbon layer and thesilver layer are laminated, while forming a ferromagnetic foil fixeddirectly onto the electrolytic capacitor as the ferromagnetic portion12. The application of the carbon paste and the silver paste can beperformed using dipping, for example.

Finally, treatments to repair defects in the dielectric oxide film 22and to insulate the solid electrolyte 23 arc conducted. The treatmentsare performed by, for example, holding the resulting structure in ahigh-temperature and high-humidity atmosphere (e.g., temperature: 85° C.and relative humidity: 80% RH) at a predetermined voltage, followed bydrying. By performing the above-described steps, it is possible toproduce an electrolytic capacitor component A with the configurationshown in FIGS. 3A and B.

Although the anode valve metal 21 is provided with only one electrodelead portion in the electrolytic capacitor component A shown in FIGS. 3Aand B, the electrolytic capacitor component A of the present inventionmay have a three-terminal configuration in which the anode valve metal21 is provided with two electrode lead portions, or a four-terminalconfiguration in which both the cathode current collector 24 and theanode valve metal 21 are provided with two electrode lead portions.These configurations also can be applied to the electrolytic capacitorcomponents in the embodiments described below.

Embodiment 3

A capacitor B (hereinafter, referred to as “electrolytic capacitorcomponent B”) of the present invention that includes an electrolyticcapacitor as a capacitor unit is described with reference to FIG. 4.FIG. 4 is a schematic cross-sectional view showing one mode of theconfiguration of an electrolytic capacitor component B (capacitor)according to Embodiment 3 of the present invention.

The electrolytic capacitor component B includes: an anode valve metal21; a dielectric oxide film 22; a solid electrolyte 23; a cathodeferromagnetic current collector 31; an insulator 25 for ensuring theelectrical insulation between the anode valve metal 21 and the cathodeferromagnetic current collector 31. It should be noted that theinsulator 25 is not essential, but preferably is provided forelectrically insulating the anode valve metal 21 and the cathode currentcollector 24 reliably.

In the electrolytic capacitor component shown in FIG. 4, the cathodeferromagnetic current collector 31 serves as both a cathode currentcollector and a ferromagnetic portion of the electrolytic capacitor. Thecathode ferromagnetic current collector 31 may include a conductiveresin composition and ferromagnetic particles as the ferromagneticportion, or may include a conductive resin composition, ferromagneticparticles as the ferromagnetic portion and metal particles including ametallic material other than a ferromagnetic material. A preferablethickness of the ferromagnetic current collector 31 is in the range of50 μm to 200 μm.

The electrolytic capacitor component shown in FIG. 4 has the sameconfiguration as the electrolytic capacitor component A described inEmbodiment 2 above, except that the cathode ferromagnetic currentcollector 31 is used in place of the ferromagnetic portion 12 and thecathode current collector 24 (see FIG. 3). Therefore, the cathodeferromagnetic current collector 31 is described in the following, andthe same reference numerals are given to the same components, thedescription of which is omitted.

The total content of the ferromagnetic particles and the metal particlesin the cathode ferromagnetic current collector 31 is preferably in therange of at least 50 mass % and at most 90 mass %, more preferably inthe range of at least 60 mass % and at most 90 mass %. When the totalcontent of the ferromagnetic particles and the metal particles in thecathode ferromagnetic current collector 31 is less than 50 mass %, theconductivity of the cathode ferromagnetic current collector 31 becomestoo low. On the other hand, when the content is more than 90 mass %, thestrength with which the conductive resin composition disperses and fixesthe ferromagnetic particles and the metal particles is reduced. As themetal particles, it is preferable to use metal particles having a higherconductivity than the ferromagnetic particles. Furthermore, it ispreferable that the relative content of the ferromagnetic particles tothe total content of the ferromagnetic particles and the metal particlesis in the range of at least 50 mass % and at most 100 mass %. When thecontent is in this range, both the conductivity required for the currentcollector and the ferromagnetism required for the ferromagnetic portioncan be satisfied adequately.

The cathode ferromagnetic current collector 31 needs to have a desiredconductivity and a desired ferromagnetism, and it is preferable todetermine the content of the ferromagnetic particles first such that thedesired ferromagnetism can be obtained, and then to determine thecontent of the metal particles having higher conductivity than theferromagnetic particles such that the desired conductivity can beobtained. In terms of ensuring the conductivity of the conductive resincomposition, a configuration in which the metal particles are includedsupplementarily in the cathode ferromagnetic current collector 31 ismore preferable that a configuration in which no metal particles areincluded. With this configuration, it is possible to ensure theconductivity of the conductive resin composition, and to control theconductivity by adjusting the content of metal particles.

Preferably, the metal particles have an average particle size of atleast 0.1 μm and at most 100 μm. When the average particle size is lessthan 0.1 μm, it is difficult to obtain an effective conductivity. Whenthe average particle size is more than 100 μm, the thickness of thecathode current collector increases, which is practicallydisadvantageous.

As the material of the metal particles, it is preferable to use a metalthat is excellent in conductivity and stability (e.g., resistant tocorrosion by oxidation). Examples of such metal particles includeparticles containing at least one metal selected from the groupconsisting of silver, copper, gold and palladium as the main component,and particles containing an alloy including one or a plurality ofdifferent metals selected from the above-described metal group as themain component. It is particularly preferable that the metal particlesare silver particles, copper particles, alloy particles containingsilver particles as the main component, or alloy particles containingcopper particles as the main component. This is because silver andcopper are less expensive than gold and palladium, and have a higherconductivity than other commonly used metals.

Preferably, the conductive resin composition included in the cathodeferromagnetic current collector 31 is made of a thermosetting resin thathas conductivity after it is cured. The reason is that the ferromagneticparticles or the metal particles can be dispersed and fixed firmly in athermosetting resin composition by mixing the ferromagnetic particles orthe metal particles with an uncured thermosetting resin and thereaftercuring the thermosetting resin by heat treatment. Examples of thethermosetting resin that has conductivity at least after it is curedinclude an epoxy resin, a phenol resin and a polyimide resin. Thesethermosetting resins can be used preferably, since they are highlyreliable under extreme environmental conditions, such as hightemperatures, high humidities and low temperatures. The conductive resincomposition included in the cathode ferromagnetic current collector 31further may include a curing agent, a curing catalyst, a surfactantand/or a coupling agent.

Here, a method for producing the electrolytic capacitor component B ofthe present embodiment is described with reference to FIG. 4. It shouldbe noted that the electrolytic capacitor component B of this embodimentis produced by performing the same steps as in Embodiment 2 describedabove until after completing the formation of the solid electrolyte 23,and therefore, the redundant description is omitted.

A paste mixture is prepared in advance by mixing ferromagnetic particlesand a paste of a thermosetting resin that will later have conductivityafter curing. In the case of forming a ferromagnetic current collectorincluding metal particles, an additive and the like, a paste mixture isprepared by mixing metal particles and/or an additive, ferromagneticparticles and a paste of the thermosetting resin in this step.

After forming the solid electrolyte 23, a cathode ferromagnetic currentcollector 31 is formed. First, a carbon layer is formed by applying acarbon paste onto the surface of the solid electrolyte 23, followed bycuring the carbon paste. Subsequently, a mixture layer is formed byapplying the paste mixture onto the carbon layer, followed by curing thepaste mixture by heat treatment. This results in formation of a cathodeferromagnetic current collector 31 in which the carbon layer and themixture layer are laminated. The application of the carbon paste and thepaste mixture can be performed using dipping, for example.

Finally, treatments to repair defects in the dielectric oxide film 22and to insulate the solid electrolyte 23 are conducted. The treatmentsare performed by, for example, holding the resulting structure in ahigh-temperature and high-humidity atmosphere (e.g., temperature: 85° C.and relative humidity: 80% RH) at a predetermined voltage, followed bydrying. It is preferable to perform this step in order to produce anelectrolytic capacitor component B with excellent properties. Byperforming the above-described steps, it is possible to produce anelectrolytic capacitor component (capacitor) with the configurationshown in FIG. 4.

Embodiment 4

In Embodiment 4 of the present invention, an example in which a moduleincorporating a capacitor is produced using the capacitor shown in FIG.4 is described with reference to FIGS. 5A and B and FIGS. 6A to C. Themodule incorporating a capacitor of this embodiment includes aspirally-configured wiring (transverse coil) having its central axis ina direction parallel with the principal plane of the moduleincorporating a capacitor, and a ferromagnetic layer of the capacitorserves as the magnetic core. FIG. 5A is a schematic cross-sectionalview, and FIG. 5B is a semi-exposed plan view, viewed from the upperside. It should be noted that FIG. 5B shows only representativecomponents that are necessary to describe the characteristic features ofthe present embodiment. FIGS. 6A to C are schematic cross-sectionalviews for illustrating the respective steps of a production process ofthe module incorporating a capacitor of the present embodiment.

In the module incorporating a capacitor shown in FIGS. 5A and B, a firstcircuit board 53 a including: three wiring layers 41 including a firstwiring layer 41 a; two electrically insulating layers 43; and aplurality of via contacts 44 embedded in the two electrically insulatinglayers 43 is provided first. On the first circuit board 53 a, acapacitor-incorporating layer 43 a is arranged which includes: aconductive adhesive portion 42 disposed on the first wiring layer 41 a;an electrolytic capacitor component 45 as produced in Embodiment 3 abovewhich is electrically connected to the first wiring layer 41 a via theconductive adhesive portion 42; and a plurality of via contacts 44embedded in the capacitor-incorporating layer 43 a. On thecapacitor-incorporating layer 43 a, a second circuit board 53 b isarranged which includes: three wiring layers 41 including a secondwiring layer 41 b; two electrically insulating layers 43; and aplurality of via contacts embedded in those two electrically insulatinglayers 43. Finally, all of the above-described components are integratedinto one piece.

The electrolytic capacitor component 45 is embedded in thecapacitor-incorporating layer 43 a. Here, an electrically insulatingportion is formed by the two electrically insulating layers 43 includedin the first circuit board 53 a, the capacitor-incorporating layers 43 aand the two electrically insulating layers 43 included in the secondcircuit board 53 b (a total of five insulating layers). A multi-layeredwiring group is formed by the three wiring layers 41 (including thefirst wiring layer 41 a) included in the first circuit board 53 a andthree wiring layers 41 (including the second wiring layer 41 b) includedin the second circuit board 53 b (a total of six wiring layers). Aplurality of interlayer contacts are formed by a plurality of the viacontacts 44 included in the first circuit board 53 a, the via contacts44 embedded in the capacitor-incorporating layer 43 a and a plurality ofthe via contacts 44 included in the second circuit board 53 b.

Further, the module incorporating a capacitor shown in FIGS. 5A and Bincludes a wiring (coil) that is formed by a coil wiring 41 cconstituting a portion of the multi-layered wiring group and a viacontact for the coil (not shown) constituting a portion of a pluralityof the interlayer contacts and whose magnetic core is a ferromagneticlayer 31 of the electrolytic capacitor component 45. More specificallythe coil shown in FIGS. 5A and B is formed by the coil wiring 41 cconstituting a portion of the wiring layer group made up of the wiringlayer 41 disposed in the first circuit board 53 a, the first wiringlayer 41 a and the second wiring layer 41 b, and the via contact forcoil constituting a portion of the via contact group made up of aplurality of the via contacts 44 embedded in the electrically insulatinglayer 43 disposed between the wiring layer 41 and the first wiring layer41 a disposed in the first circuit board 53 a and a plurality of the viacontacts 44 embedded in the capacitor-incorporating layer 43 a. That is,the wiring layers A1 to A16 shown in FIG. 5A are connected electricallyin the form of a coil.

A method for producing the module incorporating a capacitor ofEmbodiment 4 is described with reference to FIGS. 6A to C. The followingfour components are prepared in advance. First, as shown in FIG. 6A, thefirst circuit board 53 a is prepared, in which the three wiring layers41 including the first wiring layer 41 a exposed on the surface areformed. Second, as shown in FIG. 6B, the second circuit board 53 b isprepared, in which the three wiring layers 41 including the secondwiring layer 41 b exposed on the surface are formed. Third, a conductiveadhesive containing a conductive filler and an uncured thermosettingresin is prepared. Fourth, a sheet-like electrically insulatingsubstrate 54 including an uncured thermosetting resin composition and aninsulating filler is prepared. Additionally, as shown in FIG. 6B, theelectrically insulating substrate 54 is provided with a through hole inadvance, and a via paste 56 is filled into the through hole.

Next, the conductive adhesive is deposited on a predetermined area ofthe first wiring layer 41 a formed on the surface of the first circuitboard 53 a, and the electrolytic capacitor component 45 is transportedonto the first circuit board 53 a with a magnetic action, followed bycuring the conductive adhesive by heat treatment, thereby forming aconductive adhesive portion 42. This completes the mounting of theelectrolytic capacitor component 45 onto the first circuit board 53 a,as shown in FIG. 6A.

Next, the electrically insulating substrate 54 and the second circuitboard 53 b are laminated in the order shown in FIG. 6B on the side ofthe first circuit board 53 a onto which the electrolytic capacitorcomponent 45 is mounted, and a stop of performing heating and pressingis carried out at the same time. The heating and pressing are performed,for example, at 150° C. under a pressure of 1 MPa (10 Kg/cm²) for about15 minutes. It should be noted that the second circuit board 53 b islaminated on the electrically insulating substrate 54 such that thesecond wiring layer 41 b formed on the second circuit board 53 b is incontact with the electrically insulating substrate 54. By performingthese steps, the module incorporating a capacitor shown in FIG. 5 isproduced.

At the time of performing the heat treatment, an alternating current maybe applied to the electromagnet used for the transport operation, andthe heat treatment may be performed using electromagnetic inductionbetween the ferromagnetic material and the electromagnet, in addition toperforming an ordinary heating in the atmosphere. This makes it possibleto cure the conductive adhesive, while pressing the electrolyticcapacitor component 45, so that the electrolytic capacitor component 45can be mounted onto a desired position with high positional accuracy andstable connection resistance. The frequency and the amplitude of thealternating current to be applied and the period of time over which thealternating current is applied may be selected appropriately dependingon the temperature of the ferromagnetic portion. In order to prevent anexcessive temperature increase, the alternating current also may beapplied in a pulsed manner.

FIG. 7 shows another step performed during heat treatment. In FIG. 7,the reference numeral 48 denotes a magnet plate. As shown in FIG. 7, themagnet plate 48 is arranged on a surface of a circuit board 53 that isopposite to the surface on which the electrolytic capacitor component 45is mounted. By curing the conductive adhesive by performing heattreatment in this state, the conductive adhesive portion 42 is formed,and the electrolytic capacitor component 45 is fixed to the circuitboard 53 and is connected electrically to the first wiring layer 41 a,as shown in FIG. 5A. This step allows the electrolytic capacitorcomponent 45 to be attracted by the magnet plate 48 at the time ofcuring the conductive adhesive by heating, thereby stabilizing theaccuracy and the electrical connection during the mounting. There is noparticular limitation with respect to the magnet plate, as long as itdoes not lose its magnetic force significantly at the heat treatmenttemperature. For example, it is possible to use a ferrite magnet or arare-earth compound.

In the following, the first circuit board 53 a and the second circuitboard 53 b included in the module incorporating a capacitor aredescribed. The circuit boards 53 a and 53 b shown in FIG. 5A constitutea multi-layered circuit board including: four wiring layers 41(including the first wiring layer 41 a); three electrically insulatinglayers 43 each disposed between two adjacent wiring layers 41; and viacontacts 44 that are embedded in the electrically insulating layers 43and that electrically connects two adjacent wiring layers. There is noparticular limitation with respect to the substrate material of thecircuit board 53, and examples include a printed circuit board using aglass-epoxy substrate, a paper-phenol substrate or an aramid-epoxysubstrate as the substrate, as well as a ceramic board using an aluminasubstrate or a glass-alumina substrate as the substrate.

The wiring material that forms the wiring layers 41 may be selectedappropriately depending on the type of the circuit board 53. Forexample, it is possible to use as the wiring material, a copper foil forthe printed circuit board, and a sintered metal powder including Cu, Ag,Pd, Mo, W or the like for the ceramic board.

Preferably, the electrically insulating layers 43 disposed in thecircuit boards 53 shown in FIG. 5A are formed of the same material asthat of the capacitor-incorporating layer 43 a that will be describelater. This is because all the electrically insulating layers 43(including the capacitor-incorporating layer 43 a) in the finallyobtained module incorporating a capacitor are formed of the samematerial by selecting the same material as that of thecapacitor-incorporating layer 43 a, so that it is possible to reduceinternal stress caused by laminating different materials. This resultsin an improved reliability in the electrical connection of the moduleincorporating a capacitor.

In the following, the conductive adhesive forming the conductiveadhesive portion 42 is described. The conductive adhesive may becomposed only of an electrically conductive thermosetting resincomposition and a conductive filler, or it further may include one or aplurality of different additives. Examples of the conductivethermosetting resin composition contained in the conductive adhesiveinclude an epoxy resin, a phenol resin, a polyamide resin and apolyamide-imide resin. These resins can be used preferably because oftheir high reliability. There is no particular limitation with respectto the conductive filler contained in the conductive adhesive, as longas it has a low specific resistance and a low contact resistance, aswell as being relatively stable against acids and bases. Specificexamples of the conductive filler include a filler including one fillermetal selected from the group consisting of Ag, Cu, Au, Pd and Pt, afiller containing one filler metal selected from the above-describedgroup as the main component, and an alloy filler containing an alloyincluding one or a plurality of different filler metals selected fromthe above-described group as the main component. It is particularlypreferable that the conductive filler is an Ag filler, a Cu filler, analloy filler containing Ag as the main component, or an alloy fillercontaining Cu as the main component. This is because Ag and Cu are lessexpensive than Au, Pd and Pt, and have a higher conductivity than othercommonly used metals. As the additive added to the conductive adhesive,it is possible to use, for example, one or a plurality of differentadditives selected from the group consisting of a curing agent, a curingcatalyst, a surfactant, a coupling agent and a lubricant.

The conductive adhesive can be prepared by mixing a conductivethermosetting resin, a conductive filler and/or an additive. As themixing method, it is possible to user, for example, a mixing processusing three rolls, or a mixing process using a planetary mixer.

In the following, the sheet-like electrically insulating substrate 54,which will later become the capacitor-incorporating layer 43 a, isdescribed. Together with the thermosetting resin, the electricallyinsulating substrate may include one insulating filler, or it mayinclude a plurality of insulating fillers made of different materials.The electrically insulating substrate 54 further may include anadditive.

The electrically insulating substrate 54 can be produced by thefollowing procedure. First, a mixture is prepared by mixing apredetermined amount of a thermosetting resin, which is uncured, and apredetermined amount of an insulating filler. There is no particularlimitation with respect to the mixing method used at this time, and itis possible to use, for example, a process using a planetary mixer, aball milling process using ceramic balls, or a process using a planetarystirrer. In the case of adding an additive to the electricallyinsulating substrate 54, the additive is mixed together with thethermosetting resin and the insulating filler.

Next, the resulting mixture is processed into a sheet. There is noparticular limitation with respect to the method for processing themixture, and the method may be selected appropriately depending on thecondition of the thermosetting resin. Specific examples include doctorblading, extrusion, a process using a curtain coater and a process usinga roll coater. Particularly, doctor blading or extrusion can be usedpreferably because of their simplicity.

At the time of processing the mixture into a sheet, the viscosity of themixture may be adjusted by further adding a solvent upon mixing aninorganic filler and a thermosetting resin, depending on the specificprocessing method used. Examples of the solvent that can be used foradjusting the viscosity include methyl ethyl ketone (MEK), isopropanoland toluene. In the case where a solvent is added to form a sheetmember, it is necessary to remove the solvent component by performing adrying treatment on the sheet member. There is no particular limitationwith respect to the drying treatment, as long as it is performed at atemperature below the temperature at which the curing of thethermosetting resin starts.

Examples of the thermosetting resin that can be used for forming theelectrically insulating substrate 54 includes an epoxy resin, a phenolresin, an isocyanate resin and a polyamide-imide resin. These resins canbe used preferably because of their high reliability.

As the insulating filler included in the electrically insulatingsubstrate 54, it is preferable to use a particulate filler with adiameter in the range of at least 0.1 μm and at most 100 μm. The mixingratio of the insulating filler in the electrically insulating substrateis preferably in the range of at least 60 mass % and at most 95 mass %,more preferably in the range of at least 70 mass % and at most 95 mass%. When the mixing ratio is less than 60 mass %, the effect resultingfrom mixing the insulating filler is reduced. When the mixing ratio ismore than 95 mass %, on the other hand, the mixture to which theinsulating filler is mixed is difficult to process into a sheet.Examples of the insulating filler include an inorganic filler. Morespecifically, it is preferable to use an inorganic filler that includesAl₂O₃, SiO₂, SiC, AlN, BN, MgO or Si₃N₄. Particularly, an inorganicfiller that includes Al₂O₃ or SiO₂ easily can be mixed with thethermosetting resin, so that the use of this filler makes it possible toproduce an electrically insulating substrate 54 in which the inorganicfiller is mixed at a high concentration (mixing ratio). Furthermore, theuse of an inorganic filler including Al₂O₃, SiC or AlN provides a higherthermal conductivity for the electrically insulating substrate 54 thanthe use of other inorganic fillers. This also results in improved heatdissipation of the capacitor-incorporating layer 43 a.

Examples of the additive contained in the electrically insulatingsubstrate 54 include a curing agent, a curing catalyst, a couplingagent, a surfactant and a coloring agent.

It is preferable that the electrically insulating substrate 54 has athermal expansion coefficient in the range of at least 5×10⁻⁶/K and atmost 35×10⁻⁶/K. The reason is that the difference in thermal expansioncoefficient between the electrically insulating substrate and those ofthe electrolytic capacitor, the wiring and a copper-plated layer thatare incorporated in the capacitor-incorporating layer, and an inductorand a semiconductor component, which will be described later, is smallwhen the thermal expansion coefficient is in this range. Accordingly,the generation of internal stress can be prevented, which makes themodule incorporating a capacitor reliable. It is also preferable thatthe capacitor-incorporating layer 43 a has a thermal conductivity in therange of at least 1 W/m·K and at most 10 W/m·K. This is because the heatdissipation of the capacitor-incorporating layer 43 a is favorable whenthe thermal conductivity is in this range, so that the heat generatedfrom the capacitor can be dissipated to the outside quickly.Accordingly, it is possible to suppress the temperature increase invarious circuit components incorporated in the module incorporating acapacitor and to increase their allowable current. The thermal expansioncoefficient and the thermal conductivity may be adjusted depending onthe type of the thermosetting resin or the type and the mixing ratio ofthe insulating filler that constitute the electrically insulatingsubstrate 54.

The through hole for filling the via paste 56 into the electricallyinsulating substrate may be formed using, for example, a NC punchingmachine or a carbon dioxide gas laser. Alternatively, the through holemay be formed by punching using a die.

The via paste 56 is formed by mixing a powder of conductive particlesand an uncured thermosetting resin. As the mixing method, it is possibleto use the same method as that employed for producing a resin-basedconductive adhesive. The via paste 56 may include only one kind ofconductive particles, or may include plural kinds of conductiveparticles. Examples of the conductive particles contained in the viapaste 56 include particles composed only of one metal for via pasteselected from the group consisting of Ag, Cu, Au, Pd and Pt, particlescontaining one metal for via paste selected from the above-describedgroup as the main component, particles composed only of an alloyincluding a plurality of metals for via paste selected from theabove-described group, and particles containing a plurality of metalsfor via paste selected from the above-described group as the maincomponent. As the metal particles included in the via paste 56, it isparticularly preferable to use particles composed only of Ag or Cu, orparticles composed only of an alloy including Ag or Cu. Here, “maincomponent” means a component that constitutes at least 50 mass % of themetal particles included in the via paste. “Containing a plurality ofmetals as the main component” means that a total of a plurality ofmetals constitutes at least 50 mass % of the metal particles for the viapaste.

Examples of the thermosetting resin contained in the via paste 56include an epoxy resin, a phenol resin, an isocyanate resin, polyamideresin and a polyimide resin. These resins can be used preferably becauseof their high reliability. In addition, a curing agent, a curingcatalyst, a lubricant, a coupling agent, a surfactant, a high boilingsolvent and/or a reactive diluent further may be added to the via paste56.

There is no particular limitation with respect to the method for fillingthe via paste 56 into the through hole of the electrically insulatingsubstrate 54, and it is possible to use screen printing, for example.

In the following, a step of depositing the conductive adhesive isdescribed. As the method for depositing the conductive adhesive at apredetermined area on the surface of the wiring layers 41 in the circuitboard 53, it is possible to use a printing process and a method using adispenser. Considering the productivity, it is preferable to use aprinting process using a metal mask.

The heat treatment in the step of forming the conductive adhesiveportion 42 is carried out at a temperature above the temperature atwhich the conductive thermosetting resin contained in the conductiveadhesive starts curing. When the heat treatment temperature is too high,there may be cases in which the solid electrolyte in the electrolyticcapacitor component 45 thermally decomposes, producing a harmful effecton the properties of the electrolytic capacitor. Therefore, the heattreatment is performed at a temperature below the temperature at whichthe solid electrolyte starts to thermally decompose. Preferably, theheat treatment is performed at a temperature in the range of at least80° C. and at most 80° C. for a time period in the range of at least 5minutes and at most 30 minutes.

The following describes the step of laminating the electricallyinsulating substrate 54 and the second circuit board 53 b on the circuitboard 53 to which the electrolytic capacitor component 45 is mounted,followed by heating and pressing. The heat treatment temperature in thisstep can be selected appropriately such that the thermosetting resin andthe via paste 56 that are contained in the electrically insulatingsubstrate 54 can be cured and the solid electrolyte in the electrolyticcapacitor 45 is not adversely affected. Preferably the treatmenttemperature is selected from the range of at least 120° C. and at most200° C. The electrolytic capacitor 45 is positioned in (i.e., embeddedin) the electrically insulating substrate 54. Further, the electricallyinsulating substrate 54 becomes a capacitor-incorporating layer 43 aintegrated with circuit boards 53 a and 53 b, and a first wiring layer41 a′ and a wiring layer 41 b′ of the circuit board 53 b are connectedelectrically by a via contact 56′. Preferably, the treatment pressure isselected from the range of at least 0.1 MPa and at most 3 MPa.

A conductive foil 57 forms the second wiring layer 41 b in the finallyobtained module incorporating a capacitor. Examples of the conductivefoil 57 include a copper foil, a nickel foil and an aluminum foil. Thethickness of the conductive foil 57 can be selected appropriately suchthat the second wiring layer 41 b has a desired conductivity. Generally,the thickness is in the range of at least 9 μm and at most 35 μm. Thereis no particular limitation with respect to the method for patterningthe conductive foil 57. For example, it is possible to use chemicaletching using an aqueous solution of iron chloride or copper chloride.

The circuit board 53 shown in FIG. 5 is a multi-layered circuit board.However, the circuit board 53 also may be a double-sided circuit board(circuit board including a multi-layered wiring consisting of two wiringlayers) in which the wiring layer is provided only on both sides of thesubstrate, or a single-sided circuit board (single wiring) in which thewiring layer is provided on one side of the substrate. Furthermore,although four wiring layers 41 are laminated in the circuit board 53shown in FIG. 5, the number of the layers is not limited to this.

Although a thermosetting resin is used as the resin contained in theconductive adhesive in the present embodiment, it is possible to use anyother resin that is electrically conductive and capable of fixing theelectrolytic capacitor component 45. However, in order to bond the firstwiring layer 41 a and the electrolytic capacitor component 45 firmly, itis preferable to use a conductive thermosetting resin. As the conductiveadhesive, it is also possible to use a commercially available conductiveadhesive.

In the present embodiment, a resin-based conductive adhesive is used asthe conductive adhesive for forming the conductive adhesive portion 42.However, the conductive adhesive is not limited to these, and ametal-based conductive adhesive can be used, for example. Examples ofthe metal-based conductive adhesive include a lead-tin based (Pb—Snbased) solder alloy and a lead-free, Sn-based solder alloy (an alloy ofSn with Ag, Cu, In, Zn, Bi or the like). As the conductive adhesive, aresin-based conductive adhesive is more preferable than a metal-basedconductive adhesive. The reason is that a resin-based conductiveadhesive, in particular the one containing a conductive thermosettingresin, has a lower heat curing temperature than that of a solder alloy(i.e., a metal-based conductive adhesive), and therefore suppresses thethermal damage caused to the capacitor 45, the circuit board 53 and thelike. Moreover, it is possible to avoid the situation where the cathodeferromagnetic current collector included in the electrolytic capacitorcomponent 45 forms an alloy with a solder alloy and thus causes unstableelectrical connection between the ferromagnetic current collector andthe solder alloy.

In this embodiment, a single sheet member having a thickness required toembed the electrolytic capacitor component 45 therein is used as theelectrically insulating substrate 54, as shown in FIG. 6B. However, itis also possible to use a laminate of a plurality of sheet members witha specific thickness. In this case, the thickness of the electricallyinsulating substrate 54 is adjusted to a desired thickness by selectingthe number of the laminated sheet members. In the case of using thistechnique of adjusting the thickness of the electrically insulatingsubstrate 54 with the number of the laminated sheet members, it ispossible to form all the electrically insulating layers formed on thecircuit board only by sheet members with a specific thickness withoutdepending on other incorporated circuit components, by preparing aplurality of such sheet members. Further, the electrically insulatingsubstrate 54 can be provided with a recessed portion of a desired shapeby laminating a sheet member with a specific thickness from which anunnecessary portion is removed as necessary by cutting away or punchingout, and another sheet member with a specific thickness. For example, byproviding a recessed portion of a shape substantially corresponding tothe shape of the capacitor to be embedded, it is possible to reduce thedeformation (especially, the transverse flow of the above-describedsubstances constituting the insulating substrate) of the electricallyinsulating substrate 54 in the step of performing heating and pressing.When an electrically insulating substrate 54 with a recessed portion isused, the surface flatness can be ensured at a lower treatment pressure,compared with when an electrically insulating substrate 54 without arecessed portion is used. Moreover, mechanical damage during thepressing can be reduced, since the treatment can be performed at a lowpressure. Furthermore, it is possible to prevent the positional shift ofthe via contacts 44 embedded in that electrically insulating substrate54, since the deformation of the electrically insulating substrate isreduced. This increases the positional accuracy of the via contacts 44embedded in the electrically insulating substrate 54, thus suppressingthe increase in contact resistance between the via contacts 44 and thefirst wiring layer 41 a or the disconnection between them.

In the module incorporating a capacitor shown in FIGS. 5A and B, thecoil (inductor) can be formed simultaneously with the formation of themulti-layered wiring group. Furthermore, since the electrolyticcapacitor component 45 having the ferromagnetic portion is disposed inthe coil, it is possible to increase the density of and to decrease thethickness of the module incorporating a capacitor. At the same time,since the electrolytic capacitor component 45 serves as the magneticcore of the coil, the inductance of the coil can be increased. Further,since the central axis direction (winding direction) of the coil is inthe direction of the principal plane of the module incorporating acapacitor, the number of turns of the coil can be increased withoutincreasing the substrate thickness, providing the advantage ofdecreasing the thickness and increasing the inductance. Further still,since the circuit boards 53 a and 53 b are used on both sides of themodule, it is not necessary to form each single wiring layer 41 bypatterning the conductive foil, thereby easily producing a moduleincorporating a capacitor in which a coil is embedded.

Embodiment 5

The module incorporating a capacitor of this embodiment includes aspirally-configured wiring (longitudinal coil) having its central axisin the thickness direction of the module incorporating a capacitor, andthe capacitor shown in FIG. 4 serves as the magnetic core of the coil.FIGS. 8A and B are diagrams showing the configuration of the moduleincorporating a capacitor according to the present embodiment, FIG. 8Ais a cross-sectional view, and FIG. 8B is a semi-exposed plan view,viewed from the upper side. It should be noted that FIG. 8B shows onlyrepresentative components that are necessary to describe thecharacteristic features of the present embodiment.

In the module incorporating a capacitor shown in FIGS. 8A and B, first,a first circuit board 53 a is provided which includes: three wiringlayers including a first wiring layer 41 a; two electrically insulatinglayers; and a plurality of via contacts 44 embedded in the twoelectrically insulating layers. On the first circuit board 53 a, acapacitor-incorporating layer 43 a is arranged that includes: aconductive adhesive portion 42 disposed on the first wiring layer 41 a;and an electrolytic capacitor component 45 as produced in Embodiment 3above which is electrically connected to the first wiring layer Ala viathe conductive adhesive portion 42 and is embedded in thecapacitor-incorporating layer 43 a. On the capacitor-incorporating layer43 a, a second circuit board 53 b is arranged that includes: threeelectrically insulating layers 43 including the capacitor-incorporatinglayer 43 a, three wiring layers 41 including a second wiring layer 41 bformed on the capacitor incorporating layer 43 a: a plurality of viacontacts 44 embedded in the three electrically insulating layers 43.Here, an electrically insulating portion is formed by the twoelectrically insulating layers 43 of the circuit board 53 a and thethree electrically insulating layers 43 (including thecapacitor-incorporating layer 43 a) formed on the circuit board 53 a (atotal of five insulating layers). A multi-layered wiring group is formedby the three wiring layers 41 (including the first wiring layer 41 a) ofthe circuit board 53 a and the three wiring layers 41 (including thesecond wiring layer 41 b) formed on the circuit board 53 a (a total ofsix wiring layers). Moreover, a plurality of interlayer contacts areformed by a plurality of the via contacts 44 embedded in the circuitboard 53 a and a plurality of the via contacts 44 embedded in the threeinsulating layers 43 disposed on the circuit board 53 a.

Furthermore, the module incorporating a capacitor shown in FIGS. 8A andB includes a coil that is formed by a coil wiring 41 c constituting aportion of the multi-layered wiring group and a via contact for coil 44c constituting a portion of a plurality of the interlayer contacts andwhose magnetic core is the capacitor. More specifically, the coil shownin FIGS. 8A and B is formed by the coil wiring 41 c constituting aportion of the wiring layer group made up of the first wiring layer 41a, the second wiring layer 41 b and the neighboring wiring layer 41disposed on the second wiring layer 41 b, and the via contact 44 cconstituting a portion of the via contact group made up of a pluralityof the via contacts embedded in the capacitor-incorporating layer 43 aand a plurality of the via contacts 44 embedded in the neighboringelectrically insulating layer 43 disposed on the capacitor-incorporatinglayer 43 a. That is, B1, B2, B3 and B4 shown in FIG. 8A are electricallyconnected, thereby forming a longitudinal coil.

A method for producing the module incorporating a capacitor of thepresent embodiment is described. The following three components areprepared in advance. First, as shown in FIG. 8A, a first circuit board53 a is prepared in which three wiring layers 41 including a firstwiring layer 41 a with a predetermined wiring pattern on the surface areformed. Second, a conductive adhesive containing a conductive filler andan uncured thermosetting resin is prepared. Third, three sheet-likeelectrically insulating substrates containing an uncured thermosettingresin composition and an insulating filler are prepared. Additionally,the electrically insulating substrates are provided with a through holein advance, and a via paste is filled into the through hole.

Next, similarly to Embodiment 4 above, the conductive adhesive isdeposited on a predetermined area of the first wiring layer 41 a formedon the surface of the first circuit board 53 a, and the electrolyticcapacitor component 45 is transported onto the circuit board 53 a with amagnetic action, followed by curing the conductive adhesive by heattreatment, forming a conductive adhesive portion 42. Then, theelectrically insulating substrate and the second circuit board 53 b arelaminated in this order on the side of the circuit board 53 a onto whichthe electrolytic capacitor component 45 is mounted, followed byperforming heating and pressing. The heating and pressing are performed,for example, at 150° C. under a pressure of 1 MPa (10 Kg/cm²) for about15 minutes, in the same manner as described above. Thus, the moduleincorporating a capacitor shown in FIGS. 8A and B is produced.

In the module incorporating a capacitor shown in FIGS. 8A and B, thecoil (inductor) can be formed simultaneously with the formation of themulti-layered wiring group. Furthermore, since the electrolyticcapacitor component 45 having the ferromagnetic portion is disposed inthe coil forming that inductor, it is possible to increase the densityof and to decrease the thickness of the module incorporating acapacitor. At the same time, since the ferromagnetic portion of theelectrolytic capacitor component 45 serves as the magnetic core of thecoil, it is possible to increase the inductance of the coil.

Embodiment 6

In the present embodiment, one mode of a module incorporating acapacitor that uses the capacitor of the present invention is describedwith reference to FIG. 9. FIG. 9 is a schematic cross-sectional viewshowing a module incorporating a capacitor according to this embodiment.

The module incorporating a capacitor shown in FIG. 9 includes: a circuitboard 53 that includes two wiring layers 41 including a first wiringlayer 41 a, an electrically insulating layer 43 and a plurality of viacontacts 44 embedded in the electrically insulating layer 43; aconductive adhesive portion 42 disposed on the first wiring layer 41 a;an electrolytic capacitor component 45 as produced in Embodiment 3 abovewhich is electrically connected to the first wiring layer 41 a via theconductive adhesive portion 42; a capacitor-incorporating layer 43 a; asecond wiring layer 41 b formed on the capacitor-incorporating layer 43a; an inductor component 47 electrically connected to the second wiringlayer; a second electrically insulating layer 43; a wiring layer formedon the second electrically insulating layer 43; and a through holecontact 46 formed in a through hole penetrating thecapacitor-incorporating layer. The electrolytic capacitor component 45is embedded in the capacitor-incorporating layer 43 a, and the inductorcomponent 47 is embedded in the electrically insulating layer 43disposed on the capacitor-incorporating layer 43 a. Further, theinductor component 47 is disposed directly above the electrolyticcapacitor component 45. Here, an electrically insulating portion isformed by the electrically insulating layer 43 of the circuit board 53and the two electrically insulating layers 43 (including thecapacitor-incorporating layer 43 a) disposed on the circuit board 53 (atotal of three insulating layers). A multi-layered wiring group isformed by the two wiring layers 41 (including the first wiring layer 41a) of the circuit board 53 and two wiring layers 41 (including thesecond wiring layer 41 b) disposed on the circuit board 53 (a total offour wiring layers). Moreover, a plurality of interlayer contacts areformed by a plurality of the via contacts 44 of the circuit board 53, aswell as a plurality of via contacts 44 and the through hole contact 46of the two insulating layers 43 (including the capacitor-incorporatinglayer 43 a) disposed on the circuit board 53.

A method for producing the module incorporating a capacitor shown inFIG. 9 is described. The following three components are prepared inadvance. First, a circuit board 53 is prepared in which two wiringlayers 41 including a first wiring layer 41 a exposed on the surface areformed. Second, a conductive adhesive containing a conductive filler andan uncured thermosetting resin is prepared. Third, two sheet-likeelectrically insulating substrates 54 including an uncured thermosettingresin composition and an insulating filler are prepared.

Next, similarly to Embodiment 4 above, the conductive adhesive isdeposited on a predetermined area of the first wiring layer 41 a formedon the surface of the circuit board 53, and the electrolytic capacitorcomponent 45 is transported onto the circuit board 53 with a magneticaction, followed by curing the conductive adhesive by heat treatment,forming a conductive adhesive portion 42. Subsequently, the electricallyinsulating substrate and a conductive foil are laminated on the side ofthe circuit board 53 onto which the electrolytic capacitor component 45is mounted, followed by performing heating and pressing, forming acapacitor-incorporating layer 43 a. Then, a second wiring layer 41 b isformed by patterning the conductive foil.

The conductive foil forms the second wiring layer 41 b in the finallyobtained module incorporating a capacitor. Examples of the conductivefoil include a copper foil, a nickel foil and an aluminum foil. Thethickness of the conductive foil can be selected appropriately such thatthe second wiring layer 41 b has a desired conductivity. Generally, thethickness is in the range of at least 9 μm and at most 35 μm. There isno particular limitation with respect to the method for patterning theconductive foil. For example, it is possible to perform chemical etchingusing an aqueous solution of iron chloride or copper chloride.

Next, the inductor component 47 is mounted onto the second wiring layer41 b, and the electrically insulating substrate and a conductive foilare laminated on the side of the circuit board 53 onto which theinductor component 47 is mounted by the same method as that used forforming the capacitor-incorporating layer 43 a, followed by performingheating and pressing. Consequently, the inductor component 47 isembedded in the electrically insulating substrate 54 and theelectrically insulating substrate is cured, forming electricallyinsulating layers 43. Thus, the inductor component 47 is incorporated inthe module incorporating a capacitor.

Next, a through hole penetrating all of the layers is formed. In thisstep, it is possible to use any method that can be used for a commonprinted circuit board. For example, the through hole can be formed byprocessing using a drill.

Then, a through hole contact 46 is formed by plating the inner sidesurface of the through hole with copper. As the plating method, it ispossible to use panel plating, which can be used for a common printedcircuit board. It should be noted that the through hole contact 46 alsomay be formed after patterning the conductive foil described below. Inthis case, in order to protect the wiring layer 41 s on which the wiringpattern is formed beforehand, it is preferable to provide the wiringlayers 41 with a protective film using a resist.

Next, wiring layers 41 are formed by patterning the conductive foilexposed on the surface. By performing the above-described steps, themodule incorporating a capacitor show in FIG. 9 can be produced.

Examples of the inductor included in the inductor component 47 include awire wound inductor and a chip inductor, and it is particularlypreferable that the inductor is formed by a sheet-like coil includingone or two flat plate-shaped windings. With this preferableconfiguration, it is possible to reduce the thickness of the inductor,and hence to reduce the thickness of the module incorporating acapacitor.

The method for producing and applying the conductive adhesive, and themethod for producing the electrically insulating substrate 54 are thesame as described above in connection with Embodiment 4. Therefore, thedetailed description is omitted here. Further, the heating and pressingfor embedding the electrolytic capacitor component 45 into thecapacitor-incorporating layer 43 a and the heating and pressing forembedding the inductor component 47 into the electrically insulatinglayer 43 formed on the capacitor-incorporating layer 43 a are performedin the same manner as the heating and pressing (see FIG. 6B) forembedding the electrolytic capacitor component 45 into thecapacitor-incorporating layer 43 a in Embodiment 4 above.

Since the inductor component 47 is disposed directly above theelectrolytic capacitor component 45 in the capacitor-incorporating layershown in FIG. 9, the magnetic flux leaking into the peripheral portionof the inductor component 47 can be focused with the ferromagneticportion of the electrolytic capacitor component 45. Moreover, themagnetic permeability of the inductor can be improved and therefore theinductance is higher than when the inductor is disposed as a singlecomponent, or when it is disposed directly above a conventionalcapacitor.

Since the capacitor-incorporating layer shown in FIG. 9 uses the throughhole contact 46 formed inside the through hole, it also can be used inhigh current density applications. Although FIG. 9 only shows thethrough hole contact 46 for the capacitor-incorporating layer 43 a andthe electrically insulating layer 43 formed on the electricallyinsulating layer 43 a without showing any via contact, it is possible touse the through hole contact 46 and via contacts in combination, therebymaking it possible to use appropriately a portion with a large amount ofcurrent and a portion with a small amount that can be increased indensity.

Embodiment 7

In the present embodiment, one mode of a module incorporating acapacitor that uses the capacitor of the present invention is describedwith reference to FIG. 10 and FIGS. 11A to D. FIG. 10 is a schematiccross-sectional view showing the configuration of a module incorporatinga capacitor according to this embodiment. The module incorporating acapacitor of this embodiment includes a capacitor of the presentinvention, an inductor component, a semiconductor capacitor and a barechip semiconductor component.

The module incorporating a capacitor shown in FIG. 10 includes: acircuit board 53 that includes four wiring layers including a firstwiring layer 41 a, three electrically insulating layers and a pluralityof via contacts embedded in the three electrically insulating layers; aconductive adhesive portion 42 disposed on the first wiring layer 41 a;an electrolytic capacitor component 45 as produced in Embodiment 3 abovethat is electrically connected to the first wiring layer 41 a via theconductive adhesive portion 42; two electrically insulating layers 43that include a capacitor-incorporating layer 43 a and is disposed on thecircuit board 53; two wiring layers that include a second wiring layer41 b and are disposed on the capacitor-incorporating layer 43 a; aplurality of via contacts 44 embedded in the two electrically insulatinglayers 43 disposed on the capacitor-incorporating layer 43 a; a firstsemiconductor component 51 a and bare chip semiconductor components 52that are electrically connected to the second wiring layer 41 b; and asecond semiconductor component 51 b and an inductor component 47 thatare electrically connected to the wiring layer 41 disposed above thesecond wiring layer 41 b. The electrolytic capacitor component 45 isembedded in the capacitor-incorporating layer 43 a, the firstsemiconductor component 51 a and the bare chip semiconductor components52 are embedded in the electrically insulating layer 43 disposed on thecapacitor-incorporating layer 43 a, and the second semiconductorcomponent 51 b and the inductor component 47 are exposed on the surface.Here, an electrically insulating portion is formed by the threeelectrically insulating layers 43 of the circuit board 53 and the twoelectrically insulating layers (including the capacitor-incorporatinglayer 43 a) formed on the circuit board 53 (a total of five insulatinglayers). A multi-layered wiring group is formed by the four wiringlayers 41 (including the first wiring layer 41 a) of the circuit board53 and the two wiring layers 41 (including the second wiring layer 41 b)disposed on the circuit board (a total of six wiring layers). Moreover,a plurality of interlayer contacts are formed by a plurality of the viacontacts 44 of the circuit board 53 and a plurality of the via contacts44 of the two insulating layers 43 (including thecapacitor-incorporating layer 43 a) formed on the circuit board 53.

A method for producing a module incorporating a capacitor shown in FIG.10 is described with reference to FIGS. 11A to D. The following threecomponents are prepared in advance. First, as shown in FIG. 11A, a firstcircuit board 53 a is prepared in which four wiring layers 41 includinga first wiring layer 41 a exposed on the surface are formed. Second, aconductive adhesive containing a conductive filler and an uncuredthermosetting resin is prepared. Third, two sheet-like electricallyinsulating substrates 54 containing an uncured thermosetting resincomposition and an insulating filler are prepared. Additionally, asshown in FIG. 11B, the electrically insulating substrates 54 areprovided with a through hole in advance, and a via paste 56 is filledinto the through hole.

Next, the conductive adhesive is applied onto a predetermined area ofthe first wiring layer 41 a formed on the surface of the circuit board53. Then, the electrolytic capacitor component 45 is transported ontothe first circuit board 53 with a magnetic action, followed by curingthe conductive adhesive by heat treatment, forming a conductive adhesiveportion 42. Next, the electrically insulating substrate 54 and aconductive foil 57 are laminated on the side of the circuit board 53onto which the electrolytic capacitor component 45 is mounted, whileperforming heating and pressing at the same time, forming anelectrically insulating layer 43 a. Next, a second wiring layer 41 b isformed by patterning the conductive foil 57.

Then, as shown in FIG. 11A, the first semiconductor component 51 a andthe two bare chip semiconductor components 52 are mounted onto thesecond wiring layer 41 b. Next, the electrically insulating substrate 54and the conductive foil 57 are laminated as shown in FIG. 11B on theside of the circuit board 53 onto which the first semiconductorcomponent 61 a and the two bare chip semiconductor components 52 aremounted, while performing heating and pressing at the same time. Then, awiring layer 41 is formed by patterning the conductive foil exposed onthe surface. This completes the formation of the module incorporating acapacitor shown in FIG. 11C. Next, as shown in FIG. 11D, the secondsemiconductor component 51 b and the inductor component 47 are mountedonto the surface of the module incorporating a capacitor. By performingthese steps, it is possible to produce the module incorporating acapacitor shown in FIG. 10.

At the time of mounting the semiconductor components to be included inthe module incorporating a capacitor, it is preferable that thesemiconductor components are flip-chip mounted so as to be electricallyconnected to the wiring layers, regardless of whether they areincorporated in the module incorporating a capacitor, or mounted on thesurface of the module incorporating a capacitor. This is because when asemiconductor component is flip-chip mounted, the area required for themounting and the height of the mounted semiconductor can be made smallerthan when it is mounted by wire bonding. Accordingly the moduleincorporating a capacitor further can be increased in density anddecreased in thickness. Furthermore, when the first semiconductorcomponent 51 a is flip-chip mounted, it is possible to suppress the flowof wire resulting from the deformation of the electrically insulatingsubstrate, which may occur when it is mounted by wire bonding, in thestep of laminating the electrically insulating substrate and performingheating and pressing after mounting the first semiconductor component 51a, resulting in a higher mount reliability.

According to this embodiment, it is possible to produce a moduleincorporating a capacitor having a specific electrical function, byincorporating a capacitor of the present invention and integrating thecapacitor with semiconductor components and other capacitors. Examplesof the specific electrical function resulting from integratingcapacitors, semiconductor components and an inductor as in thisembodiment include a DC-DC converter function. In general, as thecapacitor and the inductor that form a DC-DC converter, it is necessaryto use, respectively, a capacitor with a relatively large capacitanceand an inductor with a relatively large inductance, as compared withthose forming other modules incorporating a capacitor. Therefore, whenthe module incorporating a capacitor is a DC/DC converter moduleincorporating a capacitor, the use of the electrolytic capacitorcomponent 45 of the present invention, which is a large-capacitance,thin, easy-to-handle component, produces a particularly high effect inreducing the size and thickness of the module.

FIG. 10 shows semiconductor components (the first semiconductorcomponent 11 a and the bare chip components 52) incorporated in themodule incorporating a capacitor and a semiconductor component (thesecond semiconductor component 51 b) mounted on the surface of themodule incorporating a capacitor. However, the present invention is notlimited to this configuration, and may include only the semiconductorcomponent mounted on the surface of the module incorporating acapacitor, or may include only the semiconductor components incorporatedin the module incorporating a capacitor Examples of the semiconductorcomponents incorporated in the module incorporating a capacitor includea packaged semiconductor component and a bare chip semiconductorcomponent, and it is preferable to use a bare chip semiconductorcomponent. The reason is that the use of a bare chip semiconductorcomponent can save the area required for packaging, and thus facilitatesminiaturization of the module incorporating a capacitor. As thesemiconductor component mounted on the surface of the moduleincorporating a capacitor, on the other hand, it is preferable to use apackaged semiconductor component. This is because the use of a packagedsemiconductor component can reduce the damage caused by an externalforce, as well as the malfunction caused by an external electromagneticaction.

Although in FIG. 10 the inductor component 47 is not arranged directlyabove the electrolytic capacitor component 45, it is preferable toarrange the inductor component 47 directly above the electrolyticcapacitor component 45 (see FIG. 9) as described in Embodiment 6 above,in order to increase the inductance of the inductor component 47. Themodule incorporating a capacitor of this embodiment may include, inplace of the inductor component 47, a coil wiring formed by a portion ofthe multi-layered wiring group of a circuit incorporating a capacitorand a portion of the via contact group embedded in the electricallyinsulating portion of the circuit incorporating a capacitor. Further,the module incorporating a capacitor of this embodiment may include boththe inductor component 47 and wiring forming a coil. In the case offorming the wiring forming a coil as the inductor, it is preferable toform the wiring such that the electrolytic capacitor component 45 servesas the magnetic core of the coil as described in Embodiments 5 an 6above, in order to increase the inductance of the coil.

Example 1

Example 1 of the present invention is a working example of theelectrolytic capacitor component described in Embodiment 2 above. Asolid electrolytic capacitor of the present example includes a foil-typeferromagnetic portion with an adhesive portion as the ferromagneticportion, and has a configuration similar to that of the electrolyticcapacitor component shown in FIG. 3.

First, an aluminum foil with a thickness of 100 μm was prepared as ananode valve metal, and the surface of the foil was roughened byelectrolytic etching. The surface roughening was performed by applyingan alternating current to the aluminum foil in an electrolyte containinghydrochloric acid as the main component at a concentration of 10 mass %,at a liquid temperature of 35° C. The roughened layer formed by thesurface roughening had a thickness of about 40 mm. Then, the aluminumfoil was cut into a 3 mm square region. The cut region was used as acapacitance forming portion.

Next, the aluminum foil was subjected to constant voltage formation at aforming voltage of 8 V in a 5 mass % ammonium adipate aqueous solutionwhose liquid temperature was maintained at 60° C., forming a dielectricoxide film with a thickness of 7 nm on the surface of the anode valvemetal. Next, the capacitance forming portion of the anode valve metalwas immersed in a solution containing a polythiophene monomer, aniron-based oxidant and a dopant, and a solid electrolyte was formed bychemical polymerization of the polythiophene monomer. Next, thedielectric oxide film was repaired by performing anodic oxidation againin an organic-solvent-based electrolyte.

Next, a polyimide tape with a width of 0.5 mm was attached as aninsulator to the boundary between the capacitance forming portion andthe electrode lead portion of the anode valve metal, separating theanode portion and the cathode portion. Then, a carbon layer was formedby applying a carbon paste to the solid electrolyte, followed by heattreatment. Furthermore, an Ag layer was formed by applying an Ag pasteto the surface of the carbon layer, followed by drying, thereby forminga cathode current collector made up of the carbon layer and the Ag layerNext, a self-adhesive iron foil (manufactured by Sekisui Chemical Co.,Ltd.) with a thickness of 25 μm was punched into a T-shape, and attachedto one side of the cathode current collector. This formed aferromagnetic portion (foil-type ferromagnetic portion with an adhesive)on the current collector.

Finally, the electrode lead portion of the anode valve metal was formedby punching with a punching die, thereby forming a solid electrolyticcapacitor component (hereinafter, referred to as “solid electrolyticcapacitor component of Example 1) having outer dimensions of 3 mm×5 mmand a thickness of about 0.2 mm in a configuration similar to that ofthe electrolytic capacitor component shown in FIG. 3.

For comparison, a solid electrolytic capacitor component (hereinafter,referred to as “solid electrolytic capacitor component of ComparativeExample 1) was produced in the same manner as the solid electrolyticcapacitor component of Example 1, except that the self-adhesive ironfoil was not attached.

When the solid electrolytic capacitor component of Comparative Example 1was held by a chip component mounter (trademark “Panasert” manufacturedby Matsushita Electric Industrial Co., Ltd.) using air suction, thecomponent could not be held by the mounter and fell after about 30seconds. In contrast, when the solid electrolytic capacitor component ofExample 1 was attracted by a mounter using an electromagnet by amagnetic action, the electrolytic capacitor component did not fall andremained held for a period during which a magnetic field was exerted bythe electromagnet. It should be noted that the strength of the magneticfield was about 7900 A/m (about 100 Oe (oersted)), and the magneticfield was exerted for five minutes. This proved that the use of thepresent example is effective especially for holding and transporting aprofile component such as a solid electrolytic capacitor component.

Example 2

Example 2 of the present invention is a working example of theelectrolytic capacitor component described in Embodiment 2 above. Asolid electrolytic capacitor of the present example includes aparticle-dispersed ferromagnetic portion as the ferromagnetic portion,and has a configuration similar to that of the electrolytic capacitorcomponent shown in FIG. 3.

First, a paste mixture containing ferromagnetic particles was preparedby mixing 90 mass % of a powder of sendust (an alloy consisting of 5mass % Al, 10 mass % Si and the remainder Fe) having an average particlesize of 30 μm and serving as the ferromagnetic particles and 8 mass % ofepoxy resin (“Epikote 828”, manufactured by Japan Epoxy Resins Co.,Ltd.) and 2 mass % of a curing agent (“PN-23”, manufactured by AjinomotoFine-Techno Co., Inc) with three rolls.

The procedure of Example 1 was followed until after forming a cathodecurrent collector, and then the paste mixture was printed by screenprinting on the cathode current collector in a C-shape as shown in FIG.2C. Thereafter, the epoxy resin contained in the above-describedferromagnetic material in paste form was cured by heating at 120° C. forone hour, forming a ferromagnetic portion (particle-dispersedferromagnetic portion) with a thickness of about 30 μm on the cathodecurrent collector. Then, the electrode lead portion of the anode valvemetal was formed by punching with a punching die, thereby forming asolid electrolytic capacitor component having outer dimensions of 3 mm×5mm and a thickness of about 0.2 mm in a configuration similar to that ofthe electrolytic capacitor component shown in FIG. 3.

When the solid electrolytic capacitor component of the present examplewas attracted by a mounter using an electromagnet with a magnetic actionin the same manner as in Example 1, the electrolytic capacitor componentdid not fall and remained held for a period during which a magneticfield was exerted by the electromagnet. It should be noted that themagnetic field was exerted for five minutes. This proved that the use ofthe present example is effective for holding and transporting a profilecomponent such as a solid electrolytic capacitor component.

Example 3

Example 3 of the present invention is a working example of theelectrolytic capacitor component described in Embodiment 3 above. Asolid electrolytic capacitor component of the present example includes aferromagnetic current collector serving as both the cathode currentcollector and the ferromagnetic portion, and has a configuration similarto that of the electrolytic capacitor component shown in FIG. 2A.

First, a paste mixture was prepared by mixing 40 mass % of an Ag powder,45 mass % of a powder of permalloy (alloy consisting of 45 mass % Ni andthe remainder Fe) serving as the ferromagnetic particles and 15 mass %of an epoxy resin (including a curing agent) with three rolls. It shouldbe noted that this paste mixture is the material that forms theferromagnetic current collector, which serves both as the cathodecurrent collector and the ferromagnetic portion in the solidelectrolytic capacitor.

The procedure of Example 1 was followed to perform the surfaceroughening of aluminum, the formation of a dielectric oxide film, theformation of a solid electrolyte, the electrical insulation between theanode portion and the cathode portion with a polyimide tape and theformation of a carbon layer. Next, a cathode ferromagnetic currentcollector was formed by applying a paste mixture formed in advance ontothe carbon layer, followed by curing the paste mixture by heating.Thereafter, the electrode lead portion of the anode valve metal wasformed by punching with a punching die, thereby forming a solidelectrolytic capacitor component having outer dimensions of 3 mm×5 mmand a thickness of about 0.2 mm in a configuration similar to that ofthe electrolytic capacitor component shown in FIG. 4.

When the solid electrolytic capacitor component of the present examplewas held by a mounter using an electromagnet in the same manner as inExample 1, the electrolytic capacitor component did not fall andremained held for a period (five minutes) in which an magnetic field wasapplied by the electromagnet. This proved that the use of the presentexample is effective for holding and transporting a profile componentsuch as a solid electrolytic capacitor component.

Example 4

Example 4 of the present invention is a working example of the moduleincorporating a capacitor described in Embodiment 4 above. A circuitboard incorporating a capacitor component of the present example has aconfiguration similar to that of the module incorporating a capacitorshown in FIGS. 5A and B. It should be noted that reference is also madeto FIGS. 6A to C, as necessary.

In order to produce a module incorporating an electrolytic capacitor, afirst multi-layered epoxy board, a second epoxy board, an electricallyinsulating substrate and a conductive adhesive were prepared in advance.

First, a first multi-layered glass epoxy board and a secondmulti-layered glass epoxy board were prepared. In the firstmulti-layered glass epoxy board, a wiring layer is formed so as to havea wiring pattern corresponding to the electrodes of the electrolyticcapacitor, and wiring layers with a predetermined wiring pattern and viacontacts with a predetermined pattern were formed so as to form a coilwhose central axis was in the plane direction of the board. In thesecond multi-layered glass epoxy board, wiring layers with apredetermined wiring pattern and via contacts with a predeterminedpattern were formed so as to form a coil whose central axis was in theplane direction of the board. Here, the two multi-layered glass epoxyboards had configurations similar respectively to the circuit boards 53a and 53 b shown in FIG. 6B.

An electrically insulating substrate was produced as follows. A solidcomponent in which 81 mass % of a fused silica powder, 19 mass % of anepoxy resin (including a curing agent) and MEK as a solvent were mixedwith a planetary mixer. The mixing ratio (mass ratio) of the solidcomponent to the solvent was 10 to 1. A mixture film was formed byapplying the obtained mixture onto a PET carrier film by doctor blading.Next, a thermosetting sheet member with a thickness of 200 μm was formedby vaporizing the MEK contained in the mixture film. Then, a throughhole with a diameter of 0.2 mm was formed in a predetermined position ofthe thermosetting sheet member with a punching machine. Subsequently, avia paste was filled into the through hole formed in the thermosettingsheet member by a printing process, forming an electrically insulatingsubstrate. In this electrically insulating substrate, a via paste, whichlater served as a component of the coil, was formed in a predeterminedpattern. The via paste used was produced by mixing 87 mass % of a copperpowder and 13 mass % of an epoxy resin (including a curing agent) withthree rolls.

Furthermore, a conductive adhesive was produced by mixing 82 mass % of asilver powder and 18 mass % of an epoxy resin with three rolls.

The conductive adhesive was printed on the surface of the wiring layerof the first multi-layered glass epoxy board using a metal mask, andthereafter the solid electrolytic capacitor component of Example 1 wasplaced on the printed conductive adhesive, followed by heating at 120°C. for 15 minutes. Thus, the solid electrolytic capacitor component ofExample 1 was mounted onto the first multi-layered glass epoxy board.

Next, the electrically insulating substrate and the second glass epoxyboard were laminated on the first multi-layered glass epoxy board onwhich the electrolytic capacitor component was mounted, and all of thesecomponents were integrated by heating and pressing at a temperature 180°C. under a pressure of 1 MPa. This formed a circuit board incorporatinga capacitor with a configuration similar to the module incorporating acapacitor shown in FIG. 6C. Ten such circuit boards were produced.

In the circuit board incorporating a capacitor of the present example, a10-turn coil (whose number of turns was 10) was formed. This coil wasmade up of the wiring layers and the via contacts in the firstmulti-layered glass epoxy board, the wiring layers and the via contactsin the second multi-layered glass epoxy board, and the via contacts inthe electrically insulating layer. Further, the solid electrolyticcapacitor component was disposed at the core of the coil. It should benoted that the coil (the coil wiring 41 c of A1 to A16) formed in themodule incorporating a capacitor shown in FIGS. 5A and B is an 8-turncoil, which has a number of turns different from that of the coil ofpresent example.

While the solid electrolytic capacitor component of Example 1 wasincorporated in the circuit board incorporating a capacitor of thepresent example, a circuit board incorporating a capacitor forcomparison was produced in the same manner as in Example 1, except thatthe solid electrolytic capacitor component of Comparative example 1 wasused in place of the solid electrolytic capacitor component of Example1.

The magnetic permeability of the portion forming the coil was measuredfor the circuit board incorporating a capacitor of the present exampleand the circuit board incorporating a capacitor of the comparativeexample, using a BH analyzer (model number: SY-8232, manufactured byIWATSU TEST INSTRUMENTS CORPORATION). The relative permeability measuredat 100 kHz (with the permeability in vacuum taken as 1.0) was 10 whenthe electrolytic capacitor component of the present example wasincorporated, whereas it was about 1 when the electrolytic capacitorcomponent of the comparative example was incorporated. This indicatedthat the inductance of the coil is higher when the electrolyticcapacitor component of the present example was disposed in the coil,than when the conventional electrolytic capacitor component wasdisposed.

The present invention can be applied to capacitors. In particular, thepresent invention suitably can be applied to electrolytic capacitorcomponents. Furthermore, the present invention can be applied to varioussemiconductor devices and the modules incorporating a capacitor used inthe semiconductor devices.

The invention may be embodied in other forms without departing from thespirit or essential characteristics thereof. The embodiments a disclosedin this application are to be considered in all respects as illustrativeand not limiting. The scope of the invention is indicated by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are intended to be embraced therein.

1. A module incorporating a capacitor, the module comprising a circuitboard and a layer incorporating the capacitor, wherein the circuit boardincludes a wiring layer and a via contact for providing electricalconductivity to a cathode and an anode of the capacitor, wherein thelayer incorporating the capacitor is formed of an inorganic filler and acured thermosetting resin composition, and includes a ferromagneticlayer integrated with at least a portion of a surface of the capacitor,and wherein, in the circuit board or the layer incorporating thecapacitor, a coil is wound around the capacitor, or an inductorcomponent is disposed in parallel with the capacitor, wherein the coilis wound around the capacitor and is a transverse coil formed by wiringson a surface of the circuit board or the layer incorporating thecapacitor, and the ferromagnetic layer serves as a magnetic core of thecoil.
 2. The module incorporating a capacitor according to claim 1,wherein a magnetic force diffused from the inductor component isreturned to the inductor component with the ferromagnetic layer bydisposing the ferromagnetic layer at least on the inductor componentside when the capacitor and the inductor component are disposed inparallel.
 3. The module incorporating a capacitor according to claim 1,wherein the capacitor is an electrolytic capacitor comprising: a valvemetal including a capacitance forming portion and an electrode leadportion; a dielectric oxide film disposed on a surface of the valvemetal; a solid electrolyte disposed on a surface of the capacitanceforming portion, with the dielectric oxide film interposed between thesolid electrolyte and the capacitance forming portion; and a currentcollector that is disposed on a surface of the solid electrolyte and iselectrically insulated from the valve metal, and wherein theferromagnetic layer is disposed on the current collector.
 4. The moduleincorporating a capacitor according to claim 1, wherein theferromagnetic layer is a ferromagnetic foil bonded onto the capacitor.5. The module incorporating a capacitor according to claim 1, whereinthe ferromagnetic layer is formed of a mixture containing ferromagneticparticles and a resin.
 6. The module incorporating a capacitor accordingto claim 5, wherein the resin is a thermosetting resin.
 7. The moduleincorporating a capacitor according to claim 5, wherein the mixturecontaining the ferromagnetic particles and the resin is exposed on asurface of the capacitor.
 8. The module incorporating a capacitoraccording to claim 1, wherein the capacitor is an electrolytic capacitorcomprising: a valve metal including a capacitance forming portion and anelectrode lead portion; a dielectric oxide film disposed on a surface ofthe valve metal; a solid electrolyte disposed on a surface of thecapacitance forming portion, with the dielectric oxide film interposedbetween the solid electrolyte and the capacitance forming portion; and acurrent collector that is disposed on a surface of the solid electrolyteand is electrically insulated from the valve metal, and wherein thecurrent collector is formed of the mixture containing the ferromagneticparticles and the resin.
 9. The module incorporating a capacitoraccording to claim 1, wherein a surface of the ferromagnetic layer thatis not in contact with the capacitor has a shape of a concave polygon.10. The module incorporating a capacitor according to claim 9, whereinthe concave polygon is a cross-shape, a T-shape or a U-shape.
 11. Themodule incorporating a capacitor according to claim
 1. wherein thewiring layer of the circuit board and the electrodes of the capacitorare electrically connected via a conductive adhesive containing aconductive powder and a thermosetting resin.